Acknowledgement mechanisms for uplink low latency communications

ABSTRACT

Methods, systems, and devices for wireless communications are described for providing acknowledgements of grant-free uplink transmissions, which may in some cases be used for low latency communications. Approaches described herein include the use of per-user equipment (UE) acknowledgement resources assigned to UEs configured for grant-free uplink transmissions as well as the use of per-group acknowledgement resources assigned to groups of UEs configured for grant-free uplink transmissions. Dynamic puncturing of data in a shared downlink data channel may be used in the context of per-UE acknowledgement resource assignment. Corresponding grants of uplink transmission resources may be used in the context of per-group acknowledgement resources assignments.

CROSS REFERENCES

The present application for patent claims the benefit of U.S.Provisional Patent Application No. 62/553,781 by Li et al., entitled“ACKNOWLEDGEMENT MECHANISMS FOR UPLINK LOW LATENCY COMMUNICATIONS,”filed Sep. 1, 2017, assigned to the assignee hereof, and expresslyincorporated by reference herein.

BACKGROUND

The following relates generally to wireless communication, and morespecifically to acknowledgement mechanisms for uplink low latencycommunications.

Wireless communications systems are widely deployed to provide varioustypes of communication content such as voice, video, packet data,messaging, broadcast, and so on. These systems may be capable ofsupporting communication with multiple users by sharing the availablesystem resources (e.g., time, frequency, and power). Examples of suchmultiple-access systems include fourth generation (4G) systems such as aLong Term Evolution (LTE) systems or LTE-Advanced (LTE-A) systems, andfifth generation (5G) systems which may be referred to as New Radio (NR)systems. These systems may employ technologies such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal frequency division multipleaccess (OFDMA), or discrete Fourier transform-spread-OFDM (DFT-S-OFDM).A wireless multiple-access communications system may include a number ofbase stations or network access nodes, each simultaneously supportingcommunication for multiple communication devices, which may be otherwiseknown as user equipment (UE).

Some wireless communications systems may be to configured to supportmultiple classes or use cases of communications. For example, a wirelesscommunications system may support ultra-reliable and low latencycommunications (URLLC), which may be used for critical functions (e.g.,mission critical functions), and may also support enhanced mobilebroadband (eMBB) communications, which may be used for applications inwhich high data rate, high capacity, and/or wide-area coverage isdesired but for which latency and reliability are less critical than inURLLC. To support low latency communications, such as URLLC, the systemmay support grant-free uplink transmissions from a UE—e.g., uplinktransmissions via transmission resources that have not been granted tothe UE by the system. Methods to provide acknowledgements of grant-freeuplink transmissions are desired.

SUMMARY

The described techniques relate to improved methods, systems, devices,or apparatuses that support acknowledgement mechanisms for uplink lowlatency communications. In some examples, a base station may assign to auser equipment (UE) configured for low latency communications, which maybe referred to as an ultra-reliable and low latency communications(URLLC) UE, an acknowledgement resource specific to the URLLC UE—e.g., adedicated acknowledgment resource. The dedicated acknowledgementresource may, however, be part of a shared downlink data channel, andthe dedicated acknowledgement resource may remain available for downlinkdata transmissions to one or more other UEs when not carrying anacknowledgement for the URLLC UE. When the URLLC UE transmits agrant-free transmission that is received by the base station, the basestation may puncture any downlink data transmission scheduled on thededicated acknowledgment resource for another UE and instead use thededicated acknowledgement resource to send an acknowledgement of thegrant-free transmission to the URLLC UE. The base station may also sendto any UE for which the punctured downlink data transmission wasscheduled an indication that the scheduled downlink data was punctured,and as part of or in addition to the indication of puncturing, may alsosend to any such UE an indication of one or more transmissions resourcesvia which the base station will transmit the punctured data. Thus, adedicated acknowledgement resource may be provided to a URLLC UE but theunderlying transmission resource may remain available when not utilizedfor acknowledgements, which may improve resource efficiency.

In additional examples, a base station may assign to a URLLC UE anacknowledgement resource that is shared with one or more other URLLCUEs—e.g., an acknowledgement resource that is assigned to a group ofURLLC UEs, which may be referred to as a group acknowledgment resource.Though the group acknowledgement resource is shared by the multipleURLLC UEs in the group, the base station may transmit grants of uplinktransmission resources along with acknowledgements to avoidmisinterpretation of acknowledgements sent via the group acknowledgementresource. For example, when the base station simultaneously receivesgrant-free transmissions from multiple URLLC UEs from the group, thebase station may use the group acknowledgment resource to send anacknowledgement of one of the received grant-free transmissions, and thebase station may also send a grant of uplink transmission resources toany other URLLC UE in the group from which a grant-free transmission wasreceived but for which no acknowledgement was sent. The base station maysend each grant of uplink transmission resources in a search space of adownlink control channel, and the URLLC UEs in the group may beconfigured to monitor the search space after sending a grant-freetransmission. URLLC UEs to which a group acknowledgment resource hasbeen assigned may use information obtained via the group acknowledgmentresource as well as information obtained via the search space tointerpret an acknowledgement received via the group acknowledgmentresource. Thus, a single acknowledgement resource may be shared by agroup of URLLC UEs, which may improve resource efficiency whilemaintaining a sufficient level of reliability.

A method of wireless communication is described. The method may includeassigning an acknowledgement resource to a UE, the acknowledgmentresource comprising a shared downlink data channel resource alsoassigned to one or more other UEs for a downlink data transmission,receiving, from the UE, a grant-free uplink transmission, andtransmitting, to the UE via the acknowledgement resource, anacknowledgement of the grant-free uplink transmission, theacknowledgement puncturing the downlink data transmission.

An apparatus for wireless communication is described. The apparatus mayinclude means for assigning an acknowledgement resource to a UE, theacknowledgment resource comprising a shared downlink data channelresource also assigned to one or more other UEs for a downlink datatransmission, receiving, from the UE, a grant-free uplink transmission,and transmitting, to the UE via the acknowledgement resource, anacknowledgement of the grant-free uplink transmission, theacknowledgement puncturing the downlink data transmission.

Another apparatus for wireless communication is described. The apparatusmay include a processor, memory in electronic communication with theprocessor, and instructions stored in the memory. The instructions maybe operable to cause the processor to assign an acknowledgement resourceto a UE, the acknowledgment resource comprising a shared downlink datachannel resource also assigned to one or more other UEs for a downlinkdata transmission, receive, from the UE, a grant-free uplinktransmission, and transmit, to the UE via the acknowledgement resource,an acknowledgement of the grant-free uplink transmission, theacknowledgement puncturing the downlink data transmission.

A non-transitory computer readable medium for wireless communication isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to assign an acknowledgementresource to a UE, the acknowledgment resource comprising a shareddownlink data channel resource also assigned to one or more other UEsfor a downlink data transmission, receive, from the UE, a grant-freeuplink transmission, and transmit, to the UE via the acknowledgementresource, an acknowledgement of the grant-free uplink transmission, theacknowledgement puncturing the downlink data transmission.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving at least one additionalgrant-free uplink transmission from one or more additional UEs apartfrom the UE, and transmitting a grant of uplink transmission resourcesin response to the grant-free uplink transmission or the at least oneother grant-free uplink transmission from the one or more additional UEsapart from the UE that is unsuccessfully decoded. Some examples of themethod, apparatus, and non-transitory computer-readable medium describedabove may further include processes, features, means, or instructionsfor transmitting the grant of uplink transmission resources within asearch space in a control channel along with an indication of whetherthe grant of uplink transmission resources is for the UE or for the oneor more additional UEs apart from the UE.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for transmitting to the one or moreother UEs an indication of the puncturing. Some examples of the method,apparatus, and non-transitory computer-readable medium described abovemay further include processes, features, means, or instructions fortransmitting the acknowledgement and transmitting the indication in asame transmission time interval. Some examples of the method, apparatus,and non-transitory computer-readable medium described above may furtherinclude processes, features, means, or instructions for transmitting theacknowledgement in a first transmission time interval and transmittingthe indication in a second transmission time interval, the secondtransmission time interval subsequent to the first transmission timeinterval. Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for transmitting the indication via acontrol channel, a dedicated indication channel, or a combinationthereof.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, transmitting the indication ofthe puncturing comprises transmitting information regarding a subsequenttransmission, the subsequent transmission comprising data punctured bythe acknowledgement.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving data from the UE via oneor more transmission resources indicated by the acknowledgement.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, assigning, to the UE, theacknowledgement resource comprises semi-persistently assigning theacknowledgement resource to the UE. In some examples, assigning, to theUE, the acknowledgement resource comprises dynamically assigning theacknowledgement resource to the UE.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, the grant-free uplinktransmission is for ultra-reliable communications, low latencycommunications, or a combination thereof. In some examples, the downlinkdata transmission is for enhanced mobile broadband communications. Insome examples, the shared downlink data channel resource comprises aphysical downlink shared channel (PDSCH).

A method of wireless communication is described. The method may includereceiving an assignment of an acknowledgement resource, theacknowledgment resource comprising a shared downlink data channelresource available for a downlink data transmission to one or more otheruser equipments (UEs), transmitting a grant-free uplink transmission,and monitoring the acknowledgement resource for an acknowledgement ofthe grant-free uplink transmission.

An apparatus for wireless communication is described. The apparatus mayinclude means for receiving an assignment of an acknowledgementresource, the acknowledgment resource comprising a shared downlink datachannel resource, transmitting a grant-free uplink transmission, andmonitoring the acknowledgement resource for an acknowledgement of thegrant-free uplink transmission.

Another apparatus for wireless communication is described. The apparatusmay include a processor, memory in electronic communication with theprocessor, and instructions stored in the memory. The instructions maybe operable to cause the processor to receive an assignment of anacknowledgement resource, the acknowledgment resource comprising ashared downlink data channel resource available for a downlink datatransmission to one or more other user equipments (UEs), transmit agrant-free uplink transmission, and monitor the acknowledgement resourcefor an acknowledgement of the grant-free uplink transmission.

A non-transitory computer readable medium for wireless communication isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to receive an assignment ofan acknowledgement resource, the acknowledgment resource comprising ashared downlink data channel resource, transmit a grant-free uplinktransmission, and monitor the acknowledgement resource for anacknowledgement of the grant-free uplink transmission.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving the acknowledgment,wherein the acknowledgement comprises a negative acknowledgementindicating that the grant-free uplink transmission was not successfullyreceived, and retransmitting data corresponding to the grant-free uplinktransmission. In some examples, retransmitting data corresponding to thegrant-free uplink transmission comprises retransmitting datacorresponding to the grant-free uplink transmission using one or moretransmission resources indicated by the acknowledgement.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving the acknowledgment,wherein the acknowledgement comprises an affirmative acknowledgementthat the grant-free uplink transmission was successfully received, andtransmitting data using one or more transmission resources indicated bythe acknowledgement.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, receiving the assignment ofthe acknowledgement resource comprises receiving a semi-persistentassignment of the acknowledgement resource. In some examples, receivingthe assignment of the acknowledgement resource comprises receiving adynamic assignment of the acknowledgement resource. In some examples,the shared downlink data channel resource comprises a PDSCH.

A method of wireless communication is described. The method may includereceiving an assignment for a shared downlink data channel resource, theshared downlink data channel resource also assigned to at least oneother UE as an acknowledgment resource, receiving a data transmission onthe shared downlink data channel resource, receiving an indication thatdata intended for the UE was punctured by the received datatransmission, and receiving a subsequent transmission comprising thepunctured data.

An apparatus for wireless communication is described. The apparatus mayinclude means for receiving an assignment for a shared downlink datachannel resource, the shared downlink data channel resource alsoassigned to at least one other UE as an acknowledgment resource,receiving a data transmission on the shared downlink data channelresource, receiving an indication that data intended for the UE waspunctured by the received data transmission, and receiving a subsequenttransmission comprising the punctured data.

Another apparatus for wireless communication is described. The apparatusmay include a processor, memory in electronic communication with theprocessor, and instructions stored in the memory. The instructions maybe operable to cause the processor to receive an assignment for a shareddownlink data channel resource, the shared downlink data channelresource also assigned to at least one other UE as an acknowledgmentresource, receive a data transmission on the shared downlink datachannel resource, receive an indication that data intended for the UEwas punctured by the received data transmission, and receive asubsequent transmission comprising the punctured data.

A non-transitory computer readable medium for wireless communication isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to receive an assignment fora shared downlink data channel resource, the shared downlink datachannel resource also assigned to at least one other UE as anacknowledgment resource, receive a data transmission on the shareddownlink data channel resource, receive an indication that data intendedfor the UE was punctured by the received data transmission, and receivea subsequent transmission comprising the punctured data.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for discarding the data transmissionbased at least in part on the indication. Some examples of the method,apparatus, and non-transitory computer-readable medium described abovemay further include processes, features, means, or instructions forreceiving the indication via a control channel, a dedicated indicationchannel, or a combination thereof.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, receiving the indicationcomprises receiving information regarding one or more transmissionresources to be used for the subsequent transmission. In some examples,the shared downlink data channel resource comprises a PDSCH.

A method of wireless communication is described. The method may includeassigning an acknowledgement resource to a UE group comprising a firstUE and one or more additional UEs, the acknowledgment resourcecomprising a shared downlink data channel resource, receiving a firstgrant-free uplink transmission from the first UE and at least oneadditional grant-free uplink transmission from the one or moreadditional UEs, transmitting, via the acknowledgement resource, anacknowledgement of whether one of the first grant-free uplinktransmission or the at least one additional grant-free uplinktransmission is successfully decoded, and transmitting a grant of uplinktransmission resources for retransmission of data corresponding to anyof the first grant-free uplink transmission or the at least one othergrant-free uplink transmission that is unsuccessfully decoded.

An apparatus for wireless communication is described. The apparatus mayinclude means for assigning an acknowledgement resource to a UE groupcomprising a first UE and one or more additional UEs, the acknowledgmentresource comprising a shared downlink data channel resource, receiving afirst grant-free uplink transmission from the first UE and at least oneadditional grant-free uplink transmission from the one or moreadditional UEs, transmitting, via the acknowledgement resource, anacknowledgement of whether one of the first grant-free uplinktransmission or the at least one additional grant-free uplinktransmission is successfully decoded, and transmitting a grant of uplinktransmission resources for retransmission of data corresponding to anyof the first grant-free uplink transmission or the at least one othergrant-free uplink transmission that is unsuccessfully decoded.

Another apparatus for wireless communication is described. The apparatusmay include a processor, memory in electronic communication with theprocessor, and instructions stored in the memory. The instructions maybe operable to cause the processor to assign an acknowledgement resourceto a UE group comprising a first UE and one or more additional UEs, theacknowledgment resource comprising a shared downlink data channelresource, receive a first grant-free uplink transmission from the firstUE and at least one additional grant-free uplink transmission from theone or more additional UEs, transmit, via the acknowledgement resource,an acknowledgement of whether one of the first grant-free uplinktransmission or the at least one additional grant-free uplinktransmission is successfully decoded, and transmit a grant of uplinktransmission resources for retransmission of data corresponding to anyof the first grant-free uplink transmission or the at least one othergrant-free uplink transmission that is unsuccessfully decoded.

A non-transitory computer readable medium for wireless communication isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to assign an acknowledgementresource to a UE group comprising a first UE and one or more additionalUEs, the acknowledgment resource comprising a shared downlink datachannel resource, receive a first grant-free uplink transmission fromthe first UE and at least one additional grant-free uplink transmissionfrom the one or more additional UEs, transmit, via the acknowledgementresource, an acknowledgement of whether one of the first grant-freeuplink transmission or the at least one additional grant-free uplinktransmission is successfully decoded, and transmit a grant of uplinktransmission resources for retransmission of data corresponding to anyof the first grant-free uplink transmission or the at least one othergrant-free uplink transmission that is unsuccessfully decoded.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, transmitting the grant ofuplink transmission resources for retransmission of data comprisestransmitting the grant of uplink transmission resources within a searchspace in a control channel along with an indication of whether the grantof uplink transmission resources is for the first UE or for the one ormore additional UEs. In some examples, the control channel comprises aphysical downlink control channel (PDCCH). In some examples, assigningthe acknowledgement resource comprises semi-persistently assigning theacknowledgement resource to the UE group. In some examples, the shareddownlink data channel resource comprises a PDSCH. In some examples, thefirst grant-free uplink transmission and the at least one additionalgrant-free uplink transmission are for ultra-reliable communications,low latency communications, or a combination thereof.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for transmitting the acknowledgementand transmitting the grant of uplink transmission resources using asingle time transmission interval.

A method of wireless communication is described. The method may includereceiving an assignment of an acknowledgement resource, theacknowledgment resource comprising a shared downlink data channelresource also assigned to one or more other UEs, transmitting agrant-free uplink transmission, receiving an acknowledgement on theacknowledgement resource, monitoring a search space in a control channelfor a grant of uplink transmission resources for retransmission of datacorresponding to the grant-free uplink transmission, and determining,based at least in part on the monitoring, whether the acknowledgementindicates a successful decode of the grant-free uplink transmission oran unsuccessful decode of the grant-free uplink transmission.

An apparatus for wireless communication is described. The apparatus mayinclude means for receiving an assignment of an acknowledgementresource, the acknowledgment resource comprising a shared downlink datachannel resource also assigned to one or more other UEs, transmitting agrant-free uplink transmission, means for receiving an acknowledgementon the acknowledgement resource, monitoring a search space in a controlchannel for a grant of uplink transmission resources for retransmissionof data corresponding to the grant-free uplink transmission, anddetermining, based at least in part on monitoring the search space,whether the acknowledgement indicates a successful decode of thegrant-free uplink transmission or an unsuccessful decode of thegrant-free uplink transmission.

Another apparatus for wireless communication is described. The apparatusmay include a processor, memory in electronic communication with theprocessor, and instructions stored in the memory. The instructions maybe operable to cause the processor to receive an assignment of anacknowledgement resource, the acknowledgment resource comprising ashared downlink data channel resource also assigned to one or more otherUEs, transmit a grant-free uplink transmission, receive anacknowledgement on the acknowledgement resource, monitor a search spacein a control channel for a grant of uplink transmission resources forretransmission of data corresponding to the grant-free uplinktransmission, and determine, based at least in part on monitoring thesearch space, whether the acknowledgement indicates a successful decodeof the grant-free uplink transmission or an unsuccessful decode of thegrant-free uplink transmission.

A non-transitory computer readable medium for wireless communication isdescribed. The non-transitory computer-readable medium may includeinstructions operable to cause a processor to receive an assignment ofan acknowledgement resource, the acknowledgment resource comprising ashared downlink data channel resource also assigned to one or more otherUEs, transmit a grant-free uplink transmission, receive anacknowledgement on the acknowledgement resource, monitor a search spacein a control channel for a grant of uplink transmission resources forretransmission of data corresponding to the grant-free uplinktransmission, and determine, based at least in part on the monitoring,whether the acknowledgement indicates a successful decode of thegrant-free uplink transmission or an unsuccessful decode of thegrant-free uplink transmission.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for determining that theacknowledgement indicates an unsuccessful decode of the grant-freeuplink transmission based at least in part on determining that thesearch space includes a grant of uplink transmission resources forretransmission of data corresponding to the grant-free uplinktransmission. Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for retransmitting data correspondingto the grant-free uplink transmission using uplink transmissionresources granted by the grant of uplink transmission resources. Someexamples of the method, apparatus, and non-transitory computer-readablemedium described above may further include processes, features, means,or instructions for determining that the acknowledgement indicates asuccessful decode of the grant-free uplink transmission based at leastin part on determining that the search space lacks a grant of uplinktransmission resources for retransmission of data corresponding to thegrant-free uplink transmission.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for retransmitting data correspondingto the grant-free uplink transmission via subsequent grant-free uplinktransmissions prior to a termination event, wherein the terminationevent comprises a threshold number of subsequent grant-free uplinktransmissions, receipt of the acknowledgement, or a combination thereof.

In some examples of the method, apparatus, and non-transitorycomputer-readable medium described above, monitoring the search space inthe control channel for the grant of uplink transmission resourcescomprises identifying within the search space a potential grant ofuplink transmission resources for retransmission of data correspondingto the grant-free uplink transmission, and evaluating a UE identifierassociated with the potential grant. In some examples, receiving theassignment of the acknowledgement resource comprises receiving asemi-persistent assignment of the acknowledgement resource. In someexamples, the shared downlink data channel resource comprises a PDSCH.In some examples, the control channel comprises a PDCCH.

Some examples of the method, apparatus, and non-transitorycomputer-readable medium described above may further include processes,features, means, or instructions for receiving the acknowledgement andreceiving the grant within a single time transmission interval.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of a system for wireless communicationsthat supports acknowledgement mechanisms for uplink low latencycommunications in accordance with aspects of the present disclosure.

FIG. 2 illustrates an example of a system for wireless communicationsthat supports acknowledgement mechanisms for uplink low latencycommunications in accordance with aspects of the present disclosure.

FIG. 3 illustrates an example of a process flow that supportsacknowledgement mechanisms for uplink low latency communications inaccordance with aspects of the present disclosure.

FIG. 4 illustrates an example of a process flow that supportsacknowledgement mechanisms for uplink low latency communications inaccordance with aspects of the present disclosure.

FIG. 5 illustrates an example of a decision matrix that supportsacknowledgement mechanisms for uplink low latency communications inaccordance with aspects of the present disclosure.

FIGS. 6 through 7 show block diagrams of a device that supportsacknowledgement mechanisms for uplink low latency communications inaccordance with aspects of the present disclosure.

FIG. 8 illustrates a block diagram of a system including a base stationthat supports acknowledgement mechanisms for uplink low latencycommunications in accordance with aspects of the present disclosure.

FIGS. 9 through 10 show block diagrams of a device that supportsacknowledgement mechanisms for uplink low latency communications inaccordance with aspects of the present disclosure.

FIG. 11 illustrates a block diagram of a system including aultra-reliable and low latency communications (URLLC) user equipment(UE) that supports acknowledgement mechanisms for uplink low latencycommunications in accordance with aspects of the present disclosure.

FIGS. 12 through 13 show block diagrams of a device that supportsacknowledgement mechanisms for uplink low latency communications inaccordance with aspects of the present disclosure.

FIG. 14 illustrates a block diagram of a system including a non-URLLC UEthat supports acknowledgement mechanisms for uplink low latencycommunications in accordance with aspects of the present disclosure.

FIGS. 15 through 19 illustrate methods for acknowledgement mechanismsfor uplink low latency communications in accordance with aspects of thepresent disclosure.

DETAILED DESCRIPTION

Some wireless communications systems, such as, for example, fifthgeneration (5G) or New Radio (NR) systems, may support multiple classesor use cases of communications. Different classes of communications mayhave different latency requirements. For example, some communicationsmay be low latency communications with strict latency requirements,while other communications may have relatively lax latency requirements.Low latency communications may be used for use cases in which excesslatency could have adverse consequences, such as adverse safetyconsequences. For example, self-driving vehicles or wirelesslycontrolled industrial equipment may rely on low latency communications.Some low latency communications may also be subject to strictreliability requirements—e.g., the communications must be supported notonly to ensure low latency but also to ensure high reliability—and thesemay be referred to as ultra-reliable and low latency communications(URLLC). The techniques described herein may be described in terms ofURLLC communications, but it should be understood that the techniquesdescribed herein are applicable to low latency communications ingeneral, regardless of whether such communications are alsoultra-reliable.

To reduce latency, a user equipment (UE) configured for low latency orURLLC communications, which may be referred to herein as a URLLC UE, maybe configured to send grant-free uplink transmissions. That is, a URLLCUE may be configured to send uplink data transmissions to a base stationvia one or more transmission resources that have not been granted to theUE by the base station. Sending data via a grant-free uplinktransmission may beneficially reduce latency compared to, for example,requesting a grant from the base station (e.g., sending a schedulingrequest to the base station), waiting for the base station to send thegrant, and then sending the data to the base station via the grantedtransmission resources. Sending data via a grant-free uplinktransmission may, however, adversely increase a probability of collisionwith another uplink transmission—e.g., because the grant-free uplinktransmission is sent via a transmission resource that has not beengranted to the URLLC UE by the base station, one or more other uplinktransmissions may be sent by another UE using the same transmissionresource (e.g., at the same time, frequency, etc.). For example, agrant-free uplink transmission may collide with another grant-freeuplink transmission sent by another URLLC UE. As another example, agrant-free uplink transmission may collide with an uplink datatransmission sent by a different UE to which the base station previouslygranted the underlying transmission resource.

To compensate for increased collision probabilities and other concerns,a URLLC UE configured to transmit data via a grant-free uplinktransmission may be configured to retransmit the same data viasuccessive grant-free uplink transmissions up to some maximum number ofrepetitions until either the URLLC UE receives an acknowledgment from abase station indicating a successful reception and decode of thegrant-free uplink transmission by the base station. Also the URLLC UEmay receive a grant from a base station of uplink transmission resourcesthat the URLLC UE may use to retransmit the data in granted fashion, oruntil the occurrence of some other termination event.

Grant-free uplink transmissions from URLLC UEs may occur in a bursty andunpredictable fashion. For example, the base station may not be able topredict when it will receive grant-free uplink transmissions and mayreceive multiple grant-free uplink transmissions from multiple URLLC UEssimultaneously (as used herein, simultaneous means such that the sametime resource would be used for corresponding acknowledgements; e.g., asame transmission time interval). The possibly bursty and unpredictablenature of grant-free uplink transmissions may complicate the ability ofthe base station to send acknowledgements for grant-free uplinktransmissions (e.g., affirmative acknowledgements indicating successfulreceptions and decodes of grant-free uplink transmissions, which may bereferred to as ACKs, or negative acknowledgements indicatingunsuccessful receptions and decodes grant-free uplink transmissions,which may be referred to as NACKs). If the base station reserves adedicated acknowledgement resource for each URLLC UE served by the basestation—e.g., for each URLLC UE, reserves a dedicated downlinktransmission resource exclusively for transmitting acknowledgements tothat URLLC UE—some or all of the reserved downlink transmissionresources may go largely unused. Thus, reserving a dedicatedacknowledgement resource for each URLLC UE served by the base stationmay be wasteful of downlink transmission resources. But if the basestation does not reserve a dedicated acknowledgement resource for eachURLLC UE served by the base station, an unacceptable probability ofacknowledgment collisions may exist. For example, if the base stationassigns the same downlink transmission resource as an acknowledgementresource for two URLLC UEs, the two URLLC UEs may send grant-free uplinktransmissions simultaneously and subsequently monitor the same sharedacknowledgement resource. This may provide unacceptable level ofreliability as, for example, the base station may successfully decodeone of the simultaneous grant-free uplink transmissions but not theother—in such scenario, if the base station sends an ACK on the sharedacknowledgement resource, the URLLC UE that sent the unsuccessfullydecoded grant-free uplink transmission may misinterpret the ACK ascorresponding to its grant-free uplink transmission and thus may notretransmit.

Improved reliability and resource efficiency (e.g., efficiency withrespect to time, frequency, code, spatial, or spectrum resources) maytherefore be achieved by improved acknowledgement mechanisms for uplinklow latency communications, such as grant-free transmissions by URLLCUEs. For example, a base station may assign to each URLLC UE served bythe base station an acknowledgement resource specific to the URLLCUE—e.g., a downlink transmission resource not also assigned as anacknowledgement resource for any other URLLC UE—which may be referred toherein as a dedicated acknowledgement resource. The dedicatedacknowledgement resource may, however, remain available for downlinktransmissions other than acknowledgements of grant-free transmissions,thus avoiding wasting the resource when not used to send anacknowledgement to the assigned URLLC UE. As another example, a basestation may assign a single acknowledgement resource to a group of URLLCUEs—e.g., a downlink transmission resource via which the base stationwill transmit an acknowledgement for any grant-free transmission fromany URLLC UE in the group—which may be referred to herein as a groupacknowledgement resource. The base station may, however, in the event ofreceiving simultaneous grant-free uplink transmissions from multipleURLLC UEs assigned the same group acknowledgement resource, transmit anacknowledgement for one of the simultaneous grant-free uplinktransmissions via the group acknowledgement resource and transmit agrant of uplink transmission resources corresponding to each of theother simultaneous grant-free uplink transmissions, thus avoidingmisinterpretation of the acknowledgement sent via the groupacknowledgement resource. Further, techniques using dedicatedacknowledgement resources and using group acknowledgement resources maybe combined.

Aspects of the disclosure are initially described in the context of awireless communications system. Various examples of process flows forimproved acknowledgement mechanisms for uplink low latencycommunications are then described. Aspects of the disclosure are furtherillustrated by and described with reference to apparatus diagrams,system diagrams, and flowcharts that relate to acknowledgementmechanisms for uplink low latency communications.

FIG. 1 illustrates an example of a wireless communications system 100 inaccordance with various aspects of the present disclosure. The wirelesscommunications system 100 includes base stations 105, UEs 115, and acore network 130. In some examples, the wireless communications system100 may be a Long Term Evolution (LTE) network, an LTE-Advanced (LTE-A)network, or a New Radio (NR) network. In some cases, wirelesscommunications system 100 may support enhanced broadband communications,ultra-reliable (e.g., mission critical) communications, low latencycommunications, or communications with low-cost and low-complexitydevices.

Base stations 105 may wirelessly communicate with UEs 115 via one ormore base station antennas. Base stations 105 described herein mayinclude or may be referred to by those skilled in the art as a basetransceiver station, a radio base station, an access point, a radiotransceiver, a NodeB, an eNodeB (eNB), a next-generation Node B orgiga-nodeB (either of which may be referred to as a gNB), a Home NodeB,a Home eNodeB, or some other suitable terminology. Wirelesscommunications system 100 may include base stations 105 of differenttypes (e.g., macro or small cell base stations). The UEs 115 describedherein may be able to communicate with various types of base stations105 and network equipment including macro eNBs, small cell eNBs, gNBs,relay base stations, and the like. Some of the UEs 115 described hereinmay be configured to support low latency communications, ultra-reliablecommunications, or a combination thereof and may be referred to hereinas URLLC UEs.

Each base station 105 may be associated with a particular geographiccoverage area 110 in which communications with various UEs 115 issupported. Each base station 105 may provide communication coverage fora respective geographic coverage area 110 via communication links 125,and communication links 125 between a base station 105 and a UE 115 mayutilize one or more carriers. Communication links 125 shown in wirelesscommunications system 100 may include uplink transmissions from a UE 115to a base station 105, or downlink transmissions, from a base station105 to a UE 115. Downlink transmissions may also be called forward linktransmissions while uplink transmissions may also be called reverse linktransmissions.

The geographic coverage area 110 for a base station 105 may be dividedinto sectors making up only a portion of the geographic coverage area110, and each sector may be associated with a cell. For example, eachbase station 105 may provide communication coverage for a macro cell, asmall cell, a hot spot, or other types of cells, or various combinationsthereof. In some examples, a base station 105 may be movable andtherefore provide communication coverage for a moving geographiccoverage area 110. In some examples, different geographic coverage areas110 associated with different technologies may overlap, and overlappinggeographic coverage areas 110 associated with different technologies maybe supported by the same base station 105 or by different base stations105. The wireless communications system 100 may include, for example, aheterogeneous LTE/LTE-A or NR network in which different types of basestations 105 provide coverage for various geographic coverage areas 110.

The term “cell” refers to a logical communication entity used forcommunication with a base station 105 (e.g., over a carrier), and may beassociated with an identifier for distinguishing neighboring cells(e.g., a physical cell identifier (PCID), a virtual cell identifier(VCID)) operating via the same or a different carrier. In some examples,a carrier may support multiple cells, and different cells may beconfigured according to different protocol types (e.g., machine-typecommunication (MTC), narrowband Internet-of-Things (NB-IoT), enhancedmobile broadband (eMBB) communications, URLLC communications, or others)that may support different classes or uses cases of communications. Insome cases, the term “cell” may refer to a portion of a geographiccoverage area 110 (e.g., a sector) over which the logical entityoperates.

UEs 115 may be dispersed throughout the wireless communications system100, and each UE 115 may be stationary or mobile. A UE 115 may also bereferred to as a mobile device, a wireless device, a remote device, ahandheld device, or a subscriber device, or some other suitableterminology, where the “device” may also be referred to as a unit, astation, a terminal, or a client. A UE 115 may also be a personalelectronic device such as a cellular phone, a personal digital assistant(PDA), a tablet computer, a laptop computer, or a personal computer. Insome examples, a UE 115 may also refer to a wireless local loop (WLL)station, an Internet of Things (IoT) device, an Internet of Everything(IoE) device, an MTC device, an eMBB device, a URLLC device, or thelike, which may be implemented in various articles such as appliances,vehicles, meters, or the like.

Some UEs 115, such as MTC or IoT devices, may be low cost or lowcomplexity devices, and may provide for automated communication betweenmachines (e.g., via Machine-to-Machine (M2M) communication). M2Mcommunication or MTC may refer to data communication technologies thatallow devices to communicate with one another or a base station 105without human intervention. In some examples, M2M communication or MTCmay include communications from devices that integrate sensors or metersto measure or capture information and relay that information to acentral server or application program that can make use of theinformation or present the information to humans interacting with theprogram or application. Some UEs 115 may be designed to collectinformation or enable automated behavior of machines. Examples ofapplications for MTC devices include smart metering, inventorymonitoring, water level monitoring, equipment monitoring, healthcaremonitoring, wildlife monitoring, weather and geological eventmonitoring, fleet management and tracking, remote security sensing,physical access control, and transaction-based business charging.

Some UEs 115 may be configured to employ operating modes that reducepower consumption, such as half-duplex communications (e.g., a mode thatsupports one-way communication via transmission or reception, but nottransmission and reception simultaneously). In some examples half-duplexcommunications may be performed at a reduced peak rate. Other powerconservation techniques for UEs 115 include entering a power saving“deep sleep” mode when not engaging in active communications, oroperating over a limited bandwidth (e.g., according to narrowbandcommunications). In some cases, UEs 115 may be designed to supportcritical functions (e.g., mission critical functions), and a wirelesscommunications system 100 may be configured to provide ultra-reliablecommunications for these functions. In some cases, a single physicaldevice may support multiple use cases of communications—e.g., a singleUE 115 may support URLLC communications as well another use case such aseMBB communications or MTC communications.

In some cases, a UE 115 may also be able to communicate directly withother UEs 115 (e.g., using a peer-to-peer (P2P) or device-to-device(D2D) protocol). One or more of a group of UEs 115 utilizing D2Dcommunications may be within the geographic coverage area 110 of a basestation 105. Other UEs 115 in such a group may be outside the geographiccoverage area 110 of a base station 105, or be otherwise unable toreceive transmissions from a base station 105. In some cases, groups ofUEs 115 communicating via D2D communications may utilize a one-to-many(1:M) system in which each UE 115 transmits to every other UE 115 in thegroup. In some cases, a base station 105 facilitates the scheduling ofresources for D2D communications. In other cases, D2D communications arecarried out between UEs 115 without the involvement of a base station105.

Base stations 105 may communicate with the core network 130 and with oneanother. For example, base stations 105 may interface with the corenetwork 130 through backhaul links 132 (e.g., via an S1 or otherinterface). Base stations 105 may communicate with one another overbackhaul links 134 (e.g., via an X2 or other interface) either directly(e.g., directly between base stations 105) or indirectly (e.g., via corenetwork 130).

The core network 130 may provide user authentication, accessauthorization, tracking, Internet Protocol (IP) connectivity, and otheraccess, routing, or mobility functions. The core network 130 may be anevolved packet core (EPC), which may include at least one mobilitymanagement entity (MME), at least one serving gateway (S-GW), and atleast one Packet Data Network (PDN) gateway (P-GW). The MME may managenon-access stratum (e.g., control plane) functions such as mobility,authentication, and bearer management for UEs 115 served by basestations 105 associated with the EPC. User IP packets may be transferredthrough the S-GW, which itself may be connected to the P-GW. The P-GWmay provide IP address allocation as well as other functions. The P-GWmay be connected to the network operators IP services. The operators IPservices may include access to the Internet, Intranet(s), an IPMultimedia Subsystem (IMS), or a Packet-Switched (PS) Streaming Service.

At least some of the network devices, such as a base station 105, mayinclude subcomponents such as an access network entity, which may be anexample of an access node controller (ANC). Each access network entitymay communicate with UEs 115 through a number of other access networktransmission entities, which may be referred to as a radio head, a smartradio head, or a transmission/reception point (TRP). In someconfigurations, various functions of each access network entity or basestation 105 may be distributed across various network devices (e.g.,radio heads and access network controllers) or consolidated into asingle network device (e.g., a base station 105).

Wireless communications system 100 may operate using one or morefrequency bands, typically in the range of 300 MHz to 300 GHz.Generally, the region from 300 MHz to 3 GHz is known as the ultra-highfrequency (UHF) region or decimeter band, since the wavelengths rangefrom approximately one decimeter to one meter in length. UHF waves maybe blocked or redirected by buildings and environmental features.However, the waves may penetrate structures sufficiently for a macrocell to provide service to UEs 115 located indoors. Transmission of UHFwaves may be associated with smaller antennas and shorter range (e.g.,less than 100 km) compared to transmission using the smaller frequenciesand longer waves of the high frequency (HF) or very high frequency (VHF)portion of the spectrum below 300 MHz.

Wireless communications system 100 may also operate in a super highfrequency (SHF) region using frequency bands from 3 GHz to 30 GHz, alsoknown as the centimeter band. The SHF region includes bands such as the5 GHz industrial, scientific, and medical (ISM) bands, which may be usedopportunistically by devices that can tolerate interference from otherusers.

Wireless communications system 100 may also operate in an extremely highfrequency (EHF) region of the spectrum (e.g., from 30 GHz to 300 GHz),also known as the millimeter band. In some examples, wirelesscommunications system 100 may support millimeter wave (mmW)communications between UEs 115 and base stations 105, and EHF antennasof the respective devices may be even smaller and more closely spacedthan UHF antennas. In some cases, this may facilitate use of antennaarrays within a UE 115. However, the propagation of EHF transmissionsmay be subject to even greater atmospheric attenuation and shorter rangethan SHF or UHF transmissions. Techniques disclosed herein may beemployed across transmissions that use one or more different frequencyregions, and designated use of bands across these frequency regions maydiffer by country or regulating body.

In some cases, wireless communications system 100 may utilize bothlicensed and unlicensed radio frequency spectrum bands. For example,wireless communications system 100 may employ License Assisted Access(LAA), LTE-Unlicensed (LTE-U) radio access technology, or NR technologyin an unlicensed band such as the 5 GHz ISM band. When operating inunlicensed radio frequency spectrum bands, wireless devices such as basestations 105 and UEs 115 may employ listen-before-talk (LBT) proceduresto ensure a frequency channel is clear before transmitting data. In somecases, operations in unlicensed bands may be based on a CA configurationin conjunction with CCs operating in a licensed band (e.g., LAA).Operations in unlicensed spectrum may include downlink transmissions,uplink transmissions, peer-to-peer transmissions, or a combination ofthese. Duplexing in unlicensed spectrum may be based on frequencydivision duplexing (FDD), time division duplexing (TDD), or acombination of both.

In some examples, base station 105 or UE 115 may be equipped withmultiple antennas, which may be used to employ techniques such astransmit diversity, receive diversity, multiple-input multiple-output(MIMO) communications, or beamforming. For example, wirelesscommunications system 100 may use a transmission scheme between atransmitting device (e.g., a base station 105) and a receiving device(e.g., a UE 115), where the transmitting device is equipped withmultiple antennas and the receiving devices are equipped with one ormore antennas. MIMO communications may employ multipath signalpropagation to increase the spectral efficiency by transmitting orreceiving multiple signals via different spatial layers, which may bereferred to as spatial multiplexing. The multiple signals may, forexample, be transmitted by the transmitting device via differentantennas or different combinations of antennas. Likewise, the multiplesignals may be received by the receiving device via different antennasor different combinations of antennas. Each of the multiple signals maybe referred to as a separate spatial stream, and may carry bitsassociated with the same data stream (e.g., the same codeword) ordifferent data streams. Different spatial layers may be associated withdifferent antenna ports used for channel measurement and reporting. MIMOtechniques include single-user MIMO (SU-MIMO) where multiple spatiallayers are transmitted to the same receiving device, and multiple-userMIMO (MU-MIMO) where multiple spatial layers are transmitted to multipledevices.

Beamforming, which may also be referred to as spatial filtering,directional transmission, or directional reception, is a signalprocessing technique that may be used at a transmitting device or areceiving device (e.g., a base station 105 or a UE 115) to shape orsteer an antenna beam (e.g., a transmit beam or receive beam) along aspatial path between the transmitting device and the receiving device.Beamforming may be achieved by combining the signals communicated viaantenna elements of an antenna array such that signals propagating atparticular orientations with respect to an antenna array experienceconstructive interference while others experience destructiveinterference. The adjustment of signals communicated via the antennaelements may include a transmitting device or a receiving deviceapplying certain amplitude and phase offsets to signals carried via eachof the antenna elements associated with the device. The adjustmentsassociated with each of the antenna elements may be defined by abeamforming weight set associated with a particular orientation (e.g.,with respect to the antenna array of the transmitting device orreceiving device, or with respect to some other orientation).

In one example, a base station 105 may use multiple antennas or antennaarrays to conduct beamforming operations for directional communicationswith a UE 115. For instance, some signals (e.g. synchronization signals,reference signals, beam selection signals, or other control signals) maybe transmitted by a base station 105 multiple times in differentdirections, which may include a signal being transmitted according todifferent beamforming weight sets associated with different directionsof transmission. Transmissions in different beam directions may be usedto identify (e.g., by the base station 105 or a receiving device, suchas a UE 115) a beam direction for subsequent transmission and/orreception by the base station 105. Some signals, such as data signalsassociated with a particular receiving device, may be transmitted by abase station 105 in a single beam direction (e.g., a directionassociated with the receiving device, such as a UE 115). In someexamples, the beam direction associated with transmissions along asingle beam direction may be determined based at least in part on asignal that was transmitted in different beam directions. For example, aUE 115 may receive one or more of the signals transmitted by the basestation 105 in different directions, and the UE 115 may report to thebase station 105 an indication of the signal it received with a highestsignal quality, or an otherwise acceptable signal quality. Althoughthese techniques are described with reference to signals transmitted inone or more directions by a base station 105, a UE 115 may employsimilar techniques for transmitting signals multiple times in differentdirections (e.g., for identifying a beam direction for subsequenttransmission or reception by the UE 115), or transmitting a signal in asingle direction (e.g., for transmitting data to a receiving device).

A receiving device (e.g., a UE 115, which may be an example of a mmWreceiving device) may try multiple receive beams when receiving varioussignals from the base station 105, such as synchronization signals,reference signals, beam selection signals, or other control signals. Forexample, a receiving device may try multiple receive directions byreceiving via different antenna subarrays, by processing receivedsignals according to different antenna subarrays, by receiving accordingto different receive beamforming weight sets applied to signals receivedat a plurality of antenna elements of an antenna array, or by processingreceived signals according to different receive beamforming weight setsapplied to signals received at a plurality of antenna elements of anantenna array, any of which may be referred to as “listening” accordingto different receive beams or receive directions. In some examples areceiving device may use a single receive beam to receive along a singlebeam direction (e.g., when receiving a data signal). The single receivebeam may be aligned in a beam direction determined based at least inpart on listening according to different receive beam directions (e.g.,a beam direction determined to have a highest signal strength, highestsignal-to-noise ratio, or otherwise acceptable signal quality based atleast in part on listening according to multiple beam directions).

In some cases, the antennas of a base station 105 or UE 115 may belocated within one or more antenna arrays, which may support MIMOoperations, or transmit or receive beamforming. For example, one or morebase station antennas or antenna arrays may be co-located at an antennaassembly, such as an antenna tower. In some cases, antennas or antennaarrays associated with a base station 105 may be located in diversegeographic locations. A base station 105 may have an antenna array witha number of rows and columns of antenna ports that the base station 105may use to support beamforming of communications with a UE 115.Likewise, a UE 115 may have one or more antenna arrays that may supportvarious MIMO or beamforming operations.

In some cases, wireless communications system 100 may be a packet-basednetwork that operate according to a layered protocol stack. In the userplane, communications at the bearer or Packet Data Convergence Protocol(PDCP) layer may be IP-based. A Radio Link Control (RLC) layer may insome cases perform packet segmentation and reassembly to communicateover logical channels. A Medium Access Control (MAC) layer may performpriority handling and multiplexing of logical channels into transportchannels. The MAC layer may also use hybrid automatic repeat request(HARQ) to provide retransmission at the MAC layer to improve linkefficiency. In the control plane, the Radio Resource Control (RRC)protocol layer may provide establishment, configuration, and maintenanceof an RRC connection between a UE 115 and a base station 105 or corenetwork 130 supporting radio bearers for user plane data. At thePhysical (PHY) layer, transport channels may be mapped to physicalchannels.

In some cases, UEs 115 and base stations 105 may support retransmissionsof data to increase the likelihood that data is received successfully.HARQ feedback is one technique of increasing the likelihood that data isreceived correctly over a communication link 125. HARQ may include acombination of error detection (e.g., using a cyclic redundancy check(CRC)), forward error correction (FEC), and retransmission (e.g.,automatic repeat request (ARQ)). HARQ may improve throughput at the MAClayer in poor radio conditions (e.g., signal-to-noise conditions). Insome cases, a wireless device may support same-slot HARQ feedback, wherethe device may provide HARQ feedback in a specific slot for datareceived in a previous symbol in the slot. In other cases, the devicemay provide HARQ feedback in a subsequent slot, or according to someother time interval.

Time intervals in LTE or NR may be expressed in multiples of a basictime unit, which may, for example, refer to a sampling period ofT_(s)=1/30,720,000 seconds. Time intervals of a communications resourcemay be organized according to radio frames each having a duration of 10milliseconds (ms), where the frame period may be expressed asT_(f)=307,200 T_(s). The radio frames may be identified by a systemframe number (SFN) ranging from 0 to 1023. Each frame may include 10subframes numbered from 0 to 9, and each subframe may have a duration ofms. A subframe may be further divided into 2 slots each having aduration of 0.5 ms, and each slot may contain 6 or 7 modulation symbolperiods (e.g., depending on the length of the cyclic prefix prepended toeach symbol period). Excluding the cyclic prefix, each symbol period maycontain 2048 sampling periods. In some cases a subframe may be thesmallest scheduling unit of the wireless communications system 100, andmay be referred to as a transmission time interval (TTI). In othercases, a smallest scheduling unit of the wireless communications system100 may be shorter than a subframe or may be dynamically selected (e.g.,in bursts of shortened TTIs (sTTIs) or in selected component carriersusing sTTIs).

In some wireless communications systems, a slot may further be dividedinto multiple mini-slots containing one or more symbols. In someinstances, a symbol of a mini-slot or a mini-slot may be the smallestunit of scheduling. In some cases, URLLC communications, such asgrant-free uplink transmission and corresponding acknowledgements, mayuse mini slots as a transmission time intervals—e.g., a UE 115 may senda grant-free uplink transmission may in a first mini slot, and a basestation may send a responsive acknowledgement in the immediatelysubsequent mini slot—which may reduce latency. Each symbol may vary induration depending on the subcarrier spacing or frequency band ofoperation, for example. Further, some wireless communications systemsmay implement slot aggregation in which multiple slots or mini-slots areaggregated together and used for communication between a UE 115 and abase station 105.

The term “carrier” refers to a set of radio frequency spectrum resourceshaving a defined physical layer structure for supporting communicationsover a communication link 125. For example, a carrier of a communicationlink 125 may include a portion of a radio frequency spectrum band thatis operated according to physical layer channels for a given radioaccess technology. Each physical layer channel may carry user data,control information, or other signaling. A carrier may be associatedwith a pre-defined frequency channel (e.g., an E-UTRA absolute radiofrequency channel number (EARFCN)), and may be positioned according to achannel raster for discovery by UEs 115. Carriers may be downlink oruplink (e.g., in an FDD mode), or be configured to carry downlink anduplink communications (e.g., in a TDD mode). In some examples, signalwaveforms transmitted over a carrier may be made up of multiplesub-carriers (e.g., using multi-carrier modulation (MCM) techniques suchas OFDM or DFT-s-OFDM).

The organizational structure of the carriers may be different fordifferent radio access technologies (e.g., LTE, LTE-A, NR, etc.). Forexample, communications over a carrier may be organized according toTTIs or slots, each of which may include user data as well as controlinformation or signaling to support decoding the user data. A carriermay also include dedicated acquisition signaling (e.g., synchronizationsignals or system information, etc.) and control signaling thatcoordinates operation for the carrier. In some examples (e.g., in acarrier aggregation configuration), a carrier may also have acquisitionsignaling or control signaling that coordinates operations for othercarriers.

Physical channels may be multiplexed on a carrier according to varioustechniques. A physical control channel and a physical data channel maybe multiplexed on a downlink carrier, for example, using time divisionmultiplexing (TDM) techniques, frequency division multiplexing (FDM)techniques, or hybrid TDM-FDM techniques. In some examples, controlinformation transmitted in a physical control channel may be distributedbetween different control regions in a cascaded manner (e.g., between acommon control region or common search space and one or more UE-specificcontrol regions or UE-specific search spaces).

A carrier may be associated with a particular bandwidth of the radiofrequency spectrum, and in some examples the carrier bandwidth may bereferred to as a “system bandwidth” of the carrier or the wirelesscommunications system 100. For example, the carrier bandwidth may be oneof a number of predetermined bandwidths for carriers of a particularradio access technology (e.g., 1.4, 3, 5, 10, 15, 20, 40, or 80 MHz). Insome examples, each served UE 115 may be configured for operating overportions or all of the carrier bandwidth. In other examples, some UEs115 may be configured for operation using a narrowband protocol typethat is associated with a predefined portion or range (e.g., set ofsubcarriers or RBs) within a carrier (e.g., “in-band” deployment of anarrowband protocol type).

In a system employing MCM techniques, a resource element may consist ofone symbol period (e.g., a duration of one modulation symbol) and onesubcarrier, where the symbol period and subcarrier spacing are inverselyrelated. The number of bits carried by each resource element may dependon the modulation scheme (e.g., the order of the modulation scheme).Thus, the more resource elements that a UE 115 receives and the higherthe order of the modulation scheme, the higher the data rate may be forthe UE 115. In MIMO systems, a wireless communications resource mayrefer to a combination of a radio frequency spectrum resource, a timeresource, and a spatial resource (e.g., spatial layers), and the use ofmultiple spatial layers may further increase the data rate forcommunications with a UE 115.

Devices of the wireless communications system 100 (e.g., base stations105 or UEs 115) may have a hardware configuration that supportscommunications over a particular carrier bandwidth, or may beconfigurable to support communications over one of a set of carrierbandwidths. In some examples, the wireless communications system 100 mayinclude base stations 105 and/or UEs that can support simultaneouscommunications via carriers associated with more than one differentcarrier bandwidth.

Wireless communications system 100 may support communication with a UE115 on multiple cells or carriers, a feature which may be referred to ascarrier aggregation (CA) or multi-carrier operation. A UE 115 may beconfigured with multiple downlink CCs and one or more uplink CCsaccording to a carrier aggregation configuration. Carrier aggregationmay be used with both FDD and TDD component carriers.

In some cases, wireless communications system 100 may utilize enhancedcomponent carriers (eCCs). An eCC may be characterized by one or morefeatures including wider carrier or frequency channel bandwidth, shortersymbol duration, shorter TTI duration, or modified control channelconfiguration. In some cases, an eCC may be associated with a carrieraggregation configuration or a dual connectivity configuration (e.g.,when multiple serving cells have a suboptimal or non-ideal backhaullink). An eCC may also be configured for use in unlicensed spectrum orshared spectrum (e.g., where more than one operator is allowed to usethe spectrum). An eCC characterized by wide carrier bandwidth mayinclude one or more segments that may be utilized by UEs 115 that arenot capable of monitoring the whole carrier bandwidth or are otherwiseconfigured to use a limited carrier bandwidth (e.g., to conserve power).

In some cases, an eCC may utilize a different symbol duration than otherCCs, which may include use of a reduced symbol duration as compared withsymbol durations of the other CCs. A shorter symbol duration may beassociated with increased spacing between adjacent subcarriers. Adevice, such as a UE 115 or base station 105, utilizing eCCs maytransmit wideband signals (e.g., according to frequency channel orcarrier bandwidths of 20, 40, 60, 80 MHz, etc.) at reduced symboldurations (e.g., 16.67 microseconds). A TTI in eCC may consist of one ormultiple symbol periods. In some cases, the TTI duration (that is, thenumber of symbol periods in a TTI) may be variable.

Wireless communications systems such as an NR system may utilize anycombination of licensed, shared, and unlicensed spectrum bands, amongothers. The flexibility of eCC symbol duration and subcarrier spacingmay allow for the use of eCC across multiple spectrums. In someexamples, NR shared spectrum may increase spectrum utilization andspectral efficiency, specifically through dynamic vertical (e.g., acrossfrequency) and horizontal (e.g., across time) sharing of resources.

FIG. 2 illustrates an example of a wireless communications system 200that supports acknowledgement mechanisms for uplink low latencycommunications in accordance with various aspects of the presentdisclosure. In some examples, wireless communications system 200 maycomprise aspects of wireless communications system 100. Wirelesscommunications system 200 includes base station 105-a, which servescoverage area 110-a (sometimes referred to as a cell). Wirelesscommunications system 200 also includes a plurality of URLLC UEs 115-aand a plurality of non-URLLC UEs 115-b, which are each located withincoverage area 110-a and each served by base station 105-a.

FIG. 2 illustrates URLLC UEs 115-a as clustered in two geographic areasand non-URLLC UEs 115-b as clustered in another geographic area. A firstgroup 205-a of URLLC UEs 115-a is clustered in a first geographic area,and a second group 205-b of URLLC UEs 115-a is clustered in a secondarea. It is to be understood, however, that this is for illustrativepurposes only. URLLC UEs 115-a and non-URLLC UEs 115-b may begeographically distributed in any manner. For example, URLLC UEs 115-aand non-URLLC UEs 115-b may be intermingled, and, in some cases, asingle UE 115 may support both URLLC and non-URLLC communications andthus act as either a URLLC UE 115-a or a non-URLLC UE 115-b.

As explained herein, in some cases base station 105-a may assign adedicated acknowledgement resource to each URLLC UE 115-a served by basestation 105-a. For example, in the context of wireless communicationssystem 200, base station 105-a may assign a total of seven dedicatedacknowledgement resources, one to each URLLC UE 115-a served by basestation 105-a. It is to be understood that other numbers of URLLC UEs115-a are possible. An example in which base station 105-a assigns adedicated acknowledgement resource to a URLLC UE 115-a is describedbelow in reference to FIG. 3.

As also exampled herein, in some cases, base station 105-a may assign agroup acknowledgement resource to a group 205 of URLLC UEs 115-a servedby base station 105-a. For example, in the context of wirelesscommunications system 200, base station 105-a may assign a first groupacknowledgement resource to group 205-a and a second groupacknowledgement resource to group 205-b. It is to be understood thatother numbers of groups 205 of URLLC UEs 115-a are possible. It isfurther to be understood that base station 105-a may assign a groupacknowledgement resource to any number of URLLC UEs 115-a, thus treatingthem as a group 205. It is further to be understood that groups 205 neednot be based on location but can alternatively or additionally be basedon other factors, either alone or in combination, such as data demand,channel quality, etc. An example in which base station 105-a assigns agroup acknowledgement resource to multiple URLLC UEs 115-a is describedbelow in reference to FIG. 4.

In some cases, base station 105-a may assign acknowledgement resourcesto URLLC UEs 115 in round-robin fashion. For example, base station 105-amay assign a dedicated acknowledgement resource to each URLLC UE 115-aserved by base station 105-a up to some maximum number of dedicatedacknowledgement resources. The base station 105-a may thereafter assignto any URLLC UE 115 that subsequently enters coverage area 110-a anacknowledgement resource that base station 105-a already assigned to oneof the other URLLC UEs 115-a, thereby converting what was a dedicatedacknowledgement resource into a group acknowledgement resource. Thus,the number of dedicated assignment resources and group assignmentresources assigned by base station 105-a may fluctuate as the number ofnumber of URLLC UEs 115-a served by base station 105-a fluctuates, andthe membership of groups 205 may similarly fluctuate.

An acknowledgement resource—either a dedicated acknowledgment resourceor a group acknowledgment resource—may comprise any downlinktransmission resource capable of carrying an acknowledgement (ACK orNACK) from base station 105-a to a URLLC UE 115-a to which it isassigned. For example, an acknowledgement resource may comprise adownlink RB and scrambling code combination. In some examples, anacknowledgement resource may comprise a downlink data channel resource,such as a physical downlink shared channel (PDSCH) resource. Uponreceipt of a grant-free uplink transmission, base station 105-a maysubsequently send an acknowledgement of the grant-free uplinktransmission via the acknowledgement resource. In some examples, basestation 105-a may send the acknowledgement of the grant-free uplinktransmission via the acknowledgement resource in a time transmissioninterval immediately subsequent to the time transmission interval inwhich the grant-free uplink transmission was received, and the relevanttime transmission intervals may comprise either a slot or mini-slot.

FIG. 3 illustrates an example of a process flow 300 in which basestation 105-a assigns a dedicated acknowledgement resource to a URLLC UE115-a in accordance with various aspects of the present disclosure. Insome examples, process flow 300 may be implemented by aspects ofwireless communications system 100 or wireless communications system200.

At step 305, base station 105-a and URLLC UE 115-a may establishcommunication according to established connection establishmenttechniques for the wireless communications system.

At step 310, base station 105-a and another UE 115-c may also establishcommunication according to established connection establishmenttechniques for the wireless communications system. The other UE 115-cmay be another URLLC UE 115-a or may be a non-URLLC UE 115-b. Steps 305and 310 may occur in any temporal order, and may in some cases occursimultaneously.

At step 315, base station 105-a may assign to URLLC UE 115-a a dedicatedacknowledgement resource. In some cases, base station 105-a may assignthe dedicated acknowledgement resource to URLLC UE 115-a insemi-persistent fashion—e.g., via an RRC connection protocol. In somecases, base station 105-a may assign the dedicated acknowledgementresource to URLLC UE 115-a in dynamic fashion—e.g., via a downlinkcontrol channel, such as a physical downlink control channel (PDCCH).When base station 105-a assigns the dedicated acknowledgement resourceto URLLC UE 115-a in dynamic fashion, base station 105-a may change theassignment—e.g., may assign to URLLC UE 115-a different dedicatedacknowledgement resource—at some later time, including on a per-timeinterval (e.g., per slot) basis.

At step 320, base station 105-a may schedule a downlink datatransmission to the other UE 115-c via the same downlink transmissionresource assigned at step 315 to URLLC UE 115-a as a dedicatedacknowledgement resource. The dedicated acknowledgement resource may beincluded within a shared downlink data channel, such as a PDSCH. Steps315 and 320 may occur in any temporal order, and may in some cases occursimultaneously. In some examples, the other UE 115-c may be a non-URLLCUE 115-b, and the data scheduled at step 320 may comprise data for eMBBcommunications.

At step 325, URLLC UE 115-a may transmit and base station 105-a mayreceive a grant-free uplink transmission. The grant free-uplinktransmission at step 325 may be for low latency communications,ultra-reliable communications, or any combination thereof. After sendingthe grant-free uplink transmission, URLLC UE 115-a may monitor at step330 the dedicated acknowledgement resource that was assigned to URLLC UE115-a at step 315.

At step 335, base station 105-a may attempt to decode the grant-freeuplink transmission transmitted at step 325.

At step 340, base station 105-a may puncture the data associated withthe downlink data transmission scheduled at step 320. Step 340 maycomprise replacing the data scheduled at step 320 with data for anacknowledgement of the grant-free transmission received by base station105-a at step 325.

At step 345, base station 105-a may transmit, via the dedicatedassignment resource assigned, an acknowledgement of the grant-freetransmission transmitted by URLLC UE 115-a at step 325. Because theother UE 115-c was scheduled at step 320 to receive a downlink datatransmission via the dedicated assignment resource, the other UE 115-cand the URLLC UE 115-a may both receive the acknowledgement transmittedat step 345. The acknowledgment may be an ACK and indicate that thedecode attempt at step 335 was successful, or the acknowledgement may bea NACK and indicate that the decode attempt at step 335 wasunsuccessful. In some cases, base station 105-a may include as part ofthe acknowledgement (or may send to URLLC UE 115-a as part of a separatetransmission) a grant of uplink transmission resources that URLLC UE115-a may use for one or more subsequent uplink transmissions. In someexamples, base station 105-a may send the acknowledgement at step 345one transmission time interval (e.g., one slot or mini slot) after thetransmission time interval in which base station 105-a received thegrant-free uplink transmission at step 325. In some examples, basestation 105-a may not send to the URLLC UE 115-a any indication of thepuncturing that occurs at step 340—such an indication may be necessarybecause the puncturing is responsive to the grant-free uplinktransmission sent by the URLLC UE 115-a at step 325 and the puncturedresource (the dedicated acknowledgement resource) has been preassignedto the URLLC UE 115-a at step 315.

At step 350, base station 105-a may transmit to the other UE 115-c anindication of the puncturing that occurred at step 340. For example, atstep 350, base station 105-a may transmit to the other UE 115-c anindication that the data the other UE 115-c received at step 345 was notthe data that was scheduled at step 320. In some examples, base station105 may include in the indication sent at step 350 (or send as aseparate transmission to the other UE 105-c) an instruction to the otherUE 115-c to discard the data that the other UE 115-c received at step345. And in some examples, base station 105 may include in theindication sent at step 350 (or send as a separate transmission to theother UE 105-c) information regarding one or more downlink transmissionresources via which base station 105-a will transmit to the other UE115-c the data that was scheduled at step 320. Step 350 may occur afterstep 345 in some examples (e.g., one or more transmission time intervals(e.g., slot or mini slot) after step 345), and may in other examplesoccur simultaneously (e.g., in the same transmission time interval(e.g., slot or mini slot) as step 345). For example, base station 105-amay in some examples transmit the indication of puncturing sent at step350 and the acknowledgement sent at step 345 in the same transmissiontime interval (e.g., in the same slot or mini slot). Base station 105-amay transmit the indication at step 350 as part of a control channel(such as a PDCCH), via a dedicated indication channel (e.g., a channelspecific to sending indications of puncturing, which may also bededicated to UE 115-c or may be common with other UEs 115), or via acombination thereof.

After receiving the acknowledgement at step 345, URLLC UE 115-a maydetermine at step 355 whether the acknowledgement is an ACK or a NACK.If the acknowledgement is a NACK, URLLC UE 115-a may at step 360retransmit to base station 105-a data that URLLC UE 115-a previouslysent at step 325. If the acknowledgement is an ACK, URLLC UE 115-a mayat step 360 transmit to base station 105-a additional uplink data (e.g.,data other than what URLLC UE 115-a previously sent at step 325),depending on whether URLLC UE 115-a has additional data to send. If theacknowledgement received at step 345 comprised (or if base station 105-aotherwise sent to URLLC UE 115-a) a grant of uplink transmissionresources, the transmission at step 360 may be via a granted resource;otherwise, the transmission at step 360 may be a grant-freetransmission. In some cases, URLLC UE 115-a may send the transmission atstep 360 one transmission time interval (e.g., one slot or mini slot)after the transmission time interval in which base station 105-atransmitted the acknowledgement at step 345.

Separately, after receiving the indication of puncturing at step 350,the other UE 115-c may discard data it received at step 345 (in responseto an instruction from base station 105-a to discard or otherwise). Theother UE 115-c may also at step 365 receive the data it was scheduled toreceive at step 320. In some examples, the other UE 115-c may at step365 receive the data it was scheduled to receive at step 320 via one ormore transmission resources indicated by the indication of puncturing orindicated by the base station 105-a as part of a separate transmissionto the other UE 115-c. Steps 365 and 350 may occur in any temporalorder, and may in some cases occur simultaneously.

Although process flow 300 is illustrated in the context of a singleURLLC UE 115-a and a single other UE 115-c, it is to be understood thatthe same techniques could be readily extended to examples in which otherUE 115-c comprises multiple UEs 115.

The use of a dedicated acknowledgement resource wherein the dedicatedacknowledgement resource comprises a shared downlink data resource thatmay be punctured in the event of a grant-free uplink transmission mayimprove efficiency with respect to transmission resources (e.g., time,frequency, code, spatial, or spectrum resources) by providing reliableacknowledgment of grant-free uplink transmissions without tying uptransmission resources when not needed for acknowledgements thereof.

FIG. 4 illustrates an example of a process flow 400 in which basestation 105-a assigns a group acknowledgement resource to multiple URLLCUEs 115-a in accordance with various aspects of the present disclosure.In some examples, process flow 400 may be implemented by aspects ofwireless communications system 100 or wireless communications system200.

At step 405, base station 105-a and a first URLLC UE 115-a 1 mayestablish communication according to established connectionestablishment techniques for the wireless communications system.

At step 410, base station 105-a and a second URLLC UE 115-a 2 may alsoestablish communication according to established connectionestablishment techniques for the wireless communications system. Steps405 and 410 may occur in any temporal order, and may in some cases occursimultaneously.

At step 415, base station 105-a may assign to the first URLLC UE 115-a 1a group acknowledgement resource. The group acknowledgement resource maybe included within a shared downlink data channel, such as a PDSCH.

At step 420, base station 105-a may assign to the second URLLC UE 115-a2 the same group acknowledgement resource that base station 105-aassigned to the first URLLC UE 115-a 1 at step 415. Steps 415 and 420may occur in any temporal order, and may in some cases occursimultaneously.

In some cases, step 415 may comprise base station 105-a assigning to thefirst URLLC UE 115-a 1 a dedicated acknowledgement resource, but uponthe occurrence of step 420, in which that same acknowledgement resourceis assigned to the second URLLC UE 115-a 2, the dedicatedacknowledgement resource may become a group acknowledgement resource. Itis also to be understood that in some cases, the group acknowledgementresource assigned at steps 415 and 420 may also be assigned to one ormore other URLLC UEs 115-a.

Also, in some cases, base station 105-a may assign the groupacknowledgement resource at steps 415 and 420 in semi-persistentfashion—e.g., via an RRC connection protocol. In some cases, basestation 105-a may assign the group acknowledgement resource at steps 415and 420 in dynamic fashion—e.g., via a downlink control channel, such asa PDCCH. When base station 105-a assigns the dedicated acknowledgementresource in dynamic fashion, base station 105-a may change theassignment—e.g., may assign to one or both of the first URLLC UE 115-a 1or the second URLLC UE 115-a 2 a different dedicated or groupacknowledgement resource—at some later time, including on a per-timeinterval (e.g., per slot) basis. Steps 415 and 420 may occur in anytemporal order, and may in some cases occur simultaneously.

At step 425, base station 105-a may receive in the same time interval(e.g., in the same slot or mini slot) a first grant-free uplinktransmission from the first URLLC UE 115-a 1 and a second grant-freeuplink transmission from the second URLLC UE 115-a 2. The two grantfree-uplink transmissions received by base station 105-a at step 425 maybe for low latency communications, ultra-reliable communications, or anycombination thereof.

After sending the first grant-free uplink transmission, the first URLLCUE 115-a 1 may at step 430 monitor the group acknowledgement resourcethat was assigned to the URLLC UE 115-a 1 at step 415.

Likewise, after sending the second grant-free uplink transmission, thesecond URLLC UE 115-a 2 may at step 435 monitor the same groupacknowledgement resource.

At step 440, base station 105-a attempts to decode one or more thegrant-free uplink transmissions received at step 425.

At step 445, base station 105-a may transmit, via the groupacknowledgement resource assigned at steps 415 and 420, anacknowledgement regarding one of the grant-free uplink transmissionsreceived at step 425. If base station 105-a attempted to decode only oneof the grant-free uplink transmissions received at step 425, then thatis the grant-free uplink transmission for which base station 105-atransmits the acknowledgement at step 445. If base station 105-aattempted to decode multiple of the grant-free uplink transmissionsreceived at step 425, then the acknowledgement at step 445 maycorrespond to any one of the grant-free uplink transmissions received atstep 425. In some examples, if base station 105-a attempted to decodemultiple grant-free uplink transmissions received at step 425, then theacknowledgement at step 445 may correspond to one of the grant-freeuplink transmissions received at step 425 for which the decode at step440 was successful.

Any URLLC UE 115-a that shares the group assignment resource may bemonitoring the group assignment resource and thus may receive theacknowledgment transmitted by base station 105-a at step 445. Forexample, in process flow 400, both the first URLLC UE 115-a 1 and thesecond URLLC UE 115-a 2 receive the acknowledgment transmitted by basestation 105-a at step 445. In some examples, base station 105-a may sendthe acknowledgement at step 445 one transmission time interval (e.g.,one slot or mini slot) after the transmission time interval in whichbase station 105-a received the simultaneous grant-free uplinktransmissions at step 425.

The acknowledgment sent at step 445 may be an ACK and indicate that thedecode attempt at step 440 for the corresponding grant-free uplinktransmission was successful, or the acknowledgement may be a NACK andindicate that the decode attempt at step 440 for the correspondinggrant-free uplink transmission was unsuccessful. In some cases, basestation 105-a may send to URLLC UE 115-a as part of the acknowledgement(or as part of a separate transmission) a grant of uplink transmissionresources that URLLC UE 115-a may use for one or more subsequent uplinktransmissions.

In the example of process flow 400, the acknowledgement transmitted atstep 445 is an ACK indicating a successful decode of the firstgrant-free uplink transmission received from the first URLLC UE 115-a 1at step 425.

At step 450, base station 105-a may transmit one or more grants ofuplink transmission resources. Base station 105-a may transmit thegrants of uplink transmission resources within a search space includedin a control channel, such as a PDCCH. Base station 105-a may include ina grant transmitted at step 450 an indication of a particular URLLC UE115-a (or a particular plurality of URLLC UEs 115-a) to which theassociated uplink transmission resources are granted. For example, basestation 105-a may scramble or otherwise associate a grant transmitted atstep 450 with a radio network temporary identifier RNTI corresponding tothe particular URLLC UE 115-a (or particular plurality of URLLC UEs115-a) to which the associated uplink transmission resources aregranted.

Step 450 may occur after step 445 in some examples (e.g., one or moretransmission time intervals (e.g., slot or mini slot) after step 445),and may in other examples occur simultaneously (e.g., in the sametransmission time interval (e.g., slot or mini slot) as step 445). Forexample, base station 105-a may in some examples transmit a grant ofuplink transmission resources at step 450 and the acknowledgement sentat step 445 in the same transmission time interval (e.g., in the sameslot or mini slot).

In some examples, where the acknowledgement at step 445 is an ACK, step450 may comprise transmitting a grant of uplink transmission resourcesto any URLLC UE 115-a other than the URLLC UE 115-a that sent thegrant-free transmission corresponding to the ACK from which a grant-freeuplink transmission was received at step 425. In other examples, wherethe acknowledgement at step 445 is a NACK, step 450 may comprisetransmitting a grant of uplink transmission resources to the URLLC UE115-a that sent the grant-free transmission corresponding to the NACK.In the example of process flow 400, the acknowledgement transmitted atstep 445 is an ACK and corresponds to the grant-free uplink transmissionreceived from the first URLLC UE 115-a 1, and thus base station 105-atransmits at step 450 a grant of uplink transmission resources to thesecond URLLC UE 115-a 2.

Any URLLC UE 115-a that receives the acknowledgement sent at step 445via the group acknowledgement resource may thereafter determine whetherthe acknowledgement is an ACK or a NACK. Thus, in the example of processflow 400, the first URLLC UE 115-a 1 may determine at step 455 that theacknowledgement is an ACK or a NACK, and the second URLLC UE 115-a 2 maydetermine at step 460 that the same acknowledgement is an ACK.

Likewise, any URLLC UE 115-a that receives the acknowledgement sent atstep 445 via the group acknowledgement resource may thereafter determinewhether it has received a grant of uplink transmission resources. Forexample, base station 105-a may configure any URLLC UE 115-a a groupacknowledgement resource to (in response to sending a grant-free uplinktransmission and/or receiving an acknowledgement via the groupacknowledgment resource) monitor a corresponding resource, such as asearch space in a control channel, to determine whether the URLLC UE115-a has also received a grant of uplink transmission resources. Thus,in the example of process flow 400, the first URLLC UE 115-a 1 maydetermine at step 465 whether it has received a grant of uplinktransmission resources by monitoring a search space, and the secondURLLCUE 115-a 2 may determine at step 470 whether it has received agrant of uplink transmission resources by monitoring the same searchspace.

In some cases, a URLLC UE 115-a may determine whether it has received agrant of uplink transmission resources based on whether or not any grantincluded in the search space has an associated RNTI or other identifierassociated with URLLC UE 115-a. In the example of process flow 400, thefirst URLLC UE 115-a 1 has not received a grant of uplink transmissionresources, and the second URLLC UE 115-a 2 has received a grant ofuplink transmission resources; thus, both the first URLLC UE 115-a 1 andthe second URLLC UE 115-a 2 may monitor the same search space, both onlythe second URLLC UE 115-a 2 may identify that it has received a grant ofuplink transmission resources.

In some examples, if a URLLC UE 115-a receives an ACK at step 445 viathe group acknowledgement resource and determines that it did notreceive a corresponding grant of uplink transmission resources, theURLLC UE 115-a may determine that the grant-free uplink transmission theURLLC UE 115-a sent at step 425 was successfully decoded by base station105-a. Thus, in the example of process flow 400, the first URLLC UE115-a 1—which received an acknowledgement at step 445, determined atstep 455 that the acknowledgement was an ACK, and determined at step 465that it did not receive a grant of uplink transmission resources—maydetermine that the first grant-free uplink transmission that the firstURLLC UE 115-a 1 sent at step 425 was successfully decoded by the basestation 105-a.

In some examples, if a URLLC UE 115-a receives an ACK at step 445 viathe group acknowledgement resource and determines that it did receive acorresponding grant of uplink transmission resources, the URLLC UE 115-amay determine that the grant-free uplink transmission the URLLC UE 115-asent at step 425 was not successfully decoded by base station 105-a.Thus, in the example of process flow 400, the second URLLC UE 115-a2—which received an acknowledgement at step 445, determined at step 460that the acknowledgement was an ACK, and determined at step 470 that itdid receive a grant of uplink transmission resources—may determine thatthe second grant-free uplink transmission that the second URLLC UE 115-a1 sent at step 425 was not successfully decoded by the base station105-a.

In some examples, if a URLLC UE 115-a determines that the grant-freeuplink transmission the URLLC UE 115-a sent at step 425 was notsuccessfully decoded by base station 105-a, the URLLC UE 115-a mayretransmit data that it previously sent at step 425. If the URLLC UE115-a has received a grant of uplink transmission resources (e.g., atstep 450), the URLLC UE 115-a may retransmit via the granted resources;otherwise, the URLLC UE 115-a may retransmit via a repeated grant-freeuplink transmission, possibly up to some maximum number of repetitions.Thus, in the example of process flow 400, the second URLLC UE 115-a 2may at step 475 retransmit via granted uplink transmission resources(e.g., via the resources granted at step 450) data it previouslytransmitted at step 425.

Although process flow 400 is illustrated in the context of a first URLLCUE 115-a 1 and a second UE 115-a 2, it is to be understood that the sametechniques could be readily extended to examples in which any number ofURLLC UEs 115-a are assigned the same group acknowledgement resource.For example, in the example of process flow 400, the second UE 115-a 2may be representative of multiple URLLC UEs 115-a other than the firstURLLC UE 115-a 1.

FIG. 5 shows a decision matrix 600 that supports acknowledgementmechanisms for uplink low latency communications in accordance withaspects of the present disclosure. FIG. 5 may illustrate the combinationof options for a URLCC UE 115-a to which a group acknowledgementresource has been assigned in view of the possible outcomes of steps455/460 and 465/470 in process flow 400.

In a first scenario, if the URLLC UE 115-a receives an ACK via the groupacknowledgement resource but does not identify a corresponding grant ofuplink transmission resources, the URLLC UE 115-a may determine that itsprior grant-free uplink transmission was successfully decoded by basestation 105-a and thus may not retransmit the data sent via its priorgrant-free uplink transmission. The first scenario may arise, forexample, if base station base station 105-a receives the priorgrant-free uplink transmission sent by the URLLC UE 115-a, andsuccessfully decodes the prior grant-free uplink transmission sent bythe URLLC UE 115-a, regardless of whether it simultaneously received agrant-free uplink transmission from any other URLLC UE 115-a assignedthe same group acknowledgement resource. The first scenario maycorrespond, for example, to the first URLLC UE 115-a 1 in process flow400.

In a second scenario, if the URLLC UE 115-a receives an ACK via thegroup acknowledgement resource and does identify a corresponding grantof uplink transmission resources, the URLLC UE 115-a may determine thatits prior grant-free uplink transmission was not successfully decoded bybase station 105-a and thus may retransmit the data sent via its priorgrant-free uplink transmission, this time using the granted resources.The second scenario may arise, for example, if base station base station105-a receives the prior grant-free uplink transmission sent by theURLLC UE 115-a, but also simultaneously receives a grant-free uplinktransmission from one or more other URLLC UEs 115-a assigned the samegroup acknowledgement resource, and the ACK is intended for one of thoseother URLLC UEs 115-a. The first scenario may correspond, for example,to the second URLLC UE 115-a 2 in process flow 400.

In a third scenario, if the URLLC UE 115-a receives a NACK via the groupacknowledgement resource and does identify a corresponding grant ofuplink transmission resources, the URLLC UE 115-a may determine that itsprior grant-free uplink transmission was not successfully decoded bybase station 105-a and thus may retransmit the data sent via its priorgrant-free uplink transmission, this time using the granted resources.The third scenario may arise, for example, if base station 105-areceives the prior grant-free uplink transmission sent by the URLLC UE115-a, does not simultaneously receive a grant-free uplink transmissionfrom any other URLLC UE 115-a assigned the same group acknowledgementresource, but does not successfully decode the prior grant-free uplinktransmission sent by the URLLC UE 115-a.

In a fourth scenario, if the URLLC UE 115-a receives a NACK via thegroup acknowledgement resource and does not identify a correspondinggrant of uplink transmission resources, the URLLC UE 115-a may determinethat its prior grant-free uplink transmission was not successfullydecoded by base station 105-a and thus may retransmit the data sent viaits prior grant-free uplink transmission. Because in this fourthscenario the URLLC UE 115-a has received no grant of uplink transmissionresources, the URLLC UE 115-a may retransmit via one or more subsequentgrant-free uplink transmissions, possibly until one or more terminationevents occur. Termination events may include for example, receipt of anacknowledgment indicating a successful decode by base station 105-a ofthe relevant data, a grant of uplink transmission resources, or reachinga maximum number of retransmissions. The fourth scenario may arise, forexample, if base station 105-a did not receive the prior grant-freeuplink transmission sent by the URLLC UE 115-a, but did receive asimultaneous grant-free uplink transmission from one other URLLC UE115-a assigned the same group acknowledgement resource, and the NACK isintended for that other URLLC UE 115-a.

The use of both an acknowledgment and a grant to together indicatewhether a base station successfully decoded a grant-free uplinktransmission may enhance reliability, for example, by providing adouble-check for a URLLC UE 115-a. The use of both an acknowledgment anda grant to together indicate whether a base station successfully decodeda grant-free uplink transmission may also improve efficiency withrespect to transmission resources (e.g., time, frequency, code, spatial,or spectrum resources) by enabling a single acknowledgment resource tobe shared by multiple URLLC UEs 115-a while maintaining sufficientreliability.

Further, techniques using dedicated acknowledgement resources and usinggroup acknowledgement resources may be combined. For example, a basestation 105-a may configure some URLLC UEs 115-a to use dedicatedacknowledgment resources and other URLLC UEs 115-a to use groupacknowledgement resources. As another example, base station 105-a mayconfigure a URLLC UE 115-a to use a dedicated acknowledgment resourcebut later configure the same URLLC UE 115-a to use a groupacknowledgment resource—e.g., in response to additional URLLC UEs 115-aentering the coverage area 110-a served by the base station 105-a.

FIG. 6 shows a block diagram 600 of a wireless device 605 that supportsacknowledgement mechanisms for uplink low latency communications inaccordance with aspects of the present disclosure. Wireless device 605may be an example of aspects of a base station 105 as described herein.Wireless device 605 may include receiver 610, base stationcommunications manager 615, and transmitter 620. Wireless device 605 mayalso include a processor. Each of these components may be incommunication with one another (e.g., via one or more buses).

Receiver 610 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related toacknowledgement mechanisms for uplink low latency communications, etc.).Information may be passed on to other components of the device. Thereceiver 610 may be an example of aspects of the transceiver 835described with reference to FIG. 8. The receiver 610 may utilize asingle antenna or a set of antennas.

Base station communications manager 615 may be an example of aspects ofthe base station communications manager 815 described with reference toFIG. 8.

Base station communications manager 615 and/or at least some of itsvarious sub-components may be implemented in hardware, software executedby a processor, firmware, or any combination thereof. If implemented insoftware executed by a processor, the functions of the base stationcommunications manager 615 and/or at least some of its varioussub-components may be executed by a general-purpose processor, a digitalsignal processor (DSP), an application-specific integrated circuit(ASIC), an field-programmable gate array (FPGA) or other programmablelogic device, discrete gate or transistor logic, discrete hardwarecomponents, or any combination thereof designed to perform the functionsdescribed in the present disclosure. The base station communicationsmanager 615 and/or at least some of its various sub-components may bephysically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations by one or more physical devices. In some examples, basestation communications manager 615 and/or at least some of its varioussub-components may be a separate and distinct component in accordancewith various aspects of the present disclosure. In other examples, basestation communications manager 615 and/or at least some of its varioussub-components may be combined with one or more other hardwarecomponents, including but not limited to an I/O component, atransceiver, a network server, another computing device, one or moreother components described in the present disclosure, or a combinationthereof in accordance with various aspects of the present disclosure.

In some examples, base station communications manager 615 may assign anacknowledgement resource to a UE, the acknowledgment resource includinga shared downlink data channel resource also assigned to one or moreother UEs for a downlink data transmission, receive, from the UE, agrant-free uplink transmission, and transmit, to the UE via theacknowledgement resource, an acknowledgement of the grant-free uplinktransmission, the acknowledgement puncturing the downlink datatransmission.

In some examples, base station communications manager 615 may assign anacknowledgement resource to a UE group including a first UE and one ormore additional UEs, the acknowledgment resource including a shareddownlink data channel resource, receive a first grant-free uplinktransmission from the first UE and at least one additional grant-freeuplink transmission from the one or more additional UEs, transmit, viathe acknowledgement resource, an acknowledgement of whether one of thefirst grant-free uplink transmission or the at least one additionalgrant-free uplink transmission is successfully decoded, and transmit agrant of uplink transmission resources for retransmission of datacorresponding to any of the first grant-free uplink transmission or theat least one other grant-free uplink transmission that is unsuccessfullydecoded.

Transmitter 620 may transmit signals generated by other components ofthe device. In some examples, the transmitter 620 may be collocated witha receiver 610 in a transceiver module. For example, the transmitter 620may be an example of aspects of the transceiver 835 described withreference to FIG. 8. The transmitter 620 may utilize a single antenna ora set of antennas.

FIG. 7 shows a block diagram 700 of a wireless device 705 that supportsacknowledgement mechanisms for uplink low latency communications inaccordance with aspects of the present disclosure. Wireless device 705may be an example of aspects of a wireless device 605 or a base station105 as described with reference to FIG. 6. Wireless device 705 mayinclude receiver 710, base station communications manager 715, andtransmitter 720. Wireless device 705 may also include a processor. Eachof these components may be in communication with one another (e.g., viaone or more buses).

Receiver 710 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related toacknowledgement mechanisms for uplink low latency communications, etc.).Information may be passed on to other components of the device. Thereceiver 710 may be an example of aspects of the transceiver 835described with reference to FIG. 8. The receiver 710 may utilize asingle antenna or a set of antennas.

Base station communications manager 715 may be an example of aspects ofthe base station communications manager 815 described with reference toFIG. 8.

Base station communications manager 715 may also include acknowledgementresource assignment manager 725, reception manager 730, acknowledgementtransmission manager 735, and uplink grant transmission manager 740.

In some examples, acknowledgement resource assignment manager 725 mayassign an acknowledgement resource to a UE, the acknowledgment resourceincluding a shared downlink data channel resource also assigned to oneor more other UEs for a downlink data transmission. In some cases,assigning, to the UE, the acknowledgement resource includessemi-persistently assigning the acknowledgement resource to the UE. Insome cases, assigning, to the UE, the acknowledgement resource includesdynamically assigning the acknowledgement resource to the UE. In somecases, the downlink data transmission is for enhanced mobile broadbandcommunications. In some cases, the shared downlink data channel resourceincludes a PDSCH.

In some examples, reception manager 730 may receive, from the UE, agrant-free uplink transmission and receive data from the UE via one ormore transmission resources indicated by the acknowledgement. In somecases, the grant-free uplink transmission is for ultra-reliablecommunications, low latency communications, or a combination thereof. Insome examples, reception manager 730 may receive at least one additionalgrant-free uplink transmission from one or more additional UEs apartfrom the UE.

In some examples, acknowledgement transmission manager 735 may transmit,to the UE via the acknowledgement resource, an acknowledgement of thegrant-free uplink transmission, the acknowledgement puncturing thedownlink data transmission, transmit to the one or more other UEs anindication of the puncturing, transmit the acknowledgement andtransmitting the indication in a same transmission time interval,transmit the acknowledgement in a first transmission time interval andtransmitting the indication in a second transmission time interval, thesecond transmission time interval subsequent to the first transmissiontime interval, and transmit the indication via a control channel, adedicated indication channel, or a combination thereof. In some cases,transmitting the indication of the puncturing includes transmittinginformation regarding a subsequent transmission, the subsequenttransmission including data punctured by the acknowledgement.

In some additional examples, instead of assigning a dedicatedacknowledgement resource to each UE, acknowledgement resource assignmentmanager 725 may assign an acknowledgement resource to a UE groupincluding a first UE and one or more additional UEs, the acknowledgmentresource including a shared downlink data channel resource. In somecases, assigning the acknowledgement resource includes semi-persistentlyassigning the acknowledgement resource to the UE group. In some cases,the shared downlink data channel resource includes a PDSCH.

In the group acknowledgement resource scenario, reception manager 730may receive a first grant-free uplink transmission from the first UE andat least one additional grant-free uplink transmission from the one ormore additional UEs. In some cases, the first grant-free uplinktransmission and the at least one additional grant-free uplinktransmission are for ultra-reliable communications, low latencycommunications, or a combination thereof.

In the group acknowledgement resource scenario, acknowledgementtransmission manager 735 may transmit, via the acknowledgement resource,an acknowledgement of whether one of the first grant-free uplinktransmission or the at least one additional grant-free uplinktransmission is successfully decoded.

In the group acknowledgement resource scenario, uplink granttransmission manager 740 may transmit a grant of uplink transmissionresources for retransmission of data corresponding to any of the firstgrant-free uplink transmission or the at least one other grant-freeuplink transmission that is unsuccessfully decoded and transmit theacknowledgement and transmitting the grant of uplink transmissionresources using a single time transmission interval. In some cases,transmitting the grant of uplink transmission resources forretransmission of data includes transmitting the grant of uplinktransmission resources within a search space in a control channel alongwith an indication of whether the grant of uplink transmission resourcesis for the first UE or for the one or more additional UEs. In somecases, the control channel includes a physical downlink control channel(PDCCH). In some examples, uplink grant transmission manager 740 maytransmit a grant of uplink transmission resources for retransmission ofdata corresponding to the grant-free uplink transmission or the at leastone other grant-free uplink transmission from the one or more additionalUEs apart from the UE that is unsuccessfully decoded. In some examples,uplink grant transmission manager 740 may transmit the grant of uplinktransmission resources within a search space in a control channel alongwith an indication of whether the grant of uplink transmission resourcesis for the UE or for the one or more additional UEs apart from the UE.

Transmitter 720 may transmit signals generated by other components ofthe device. In some examples, the transmitter 720 may be collocated witha receiver 710 in a transceiver module. For example, the transmitter 720may be an example of aspects of the transceiver 835 described withreference to FIG. 8. The transmitter 720 may utilize a single antenna ora set of antennas.

FIG. 8 shows a diagram of a system 800 including a device 805 thatsupports acknowledgement mechanisms for uplink low latencycommunications in accordance with aspects of the present disclosure.Device 805 may be an example of or include the components of wirelessdevice 605, wireless device 705, or a base station 105 as describedabove, e.g., with reference to FIGS. 6 and 7. Device 805 may includecomponents for bi-directional voice and data communications includingcomponents for transmitting and receiving communications, including basestation communications manager 815, processor 820, memory 825, software830, transceiver 835, and I/O controller 840. These components may be inelectronic communication via one or more buses (e.g., bus 810).

Processor 820 may include an intelligent hardware device, (e.g., ageneral-purpose processor, a DSP, a central processing unit (CPU), amicrocontroller, an ASIC, an FPGA, a programmable logic device, adiscrete gate or transistor logic component, a discrete hardwarecomponent, or any combination thereof). In some cases, processor 820 maybe configured to operate a memory array using a memory controller. Inother cases, a memory controller may be integrated into processor 820.Processor 820 may be configured to execute computer-readableinstructions stored in a memory to perform various functions (e.g.,functions or tasks supporting acknowledgement mechanisms for uplink lowlatency communications).

Memory 825 may include random access memory (RAM) and read only memory(ROM). The memory 825 may store computer-readable, computer-executablesoftware 830 including instructions that, when executed, cause theprocessor to perform various functions described herein. In some cases,the memory 825 may contain, among other things, a basic input/outputsystem (BIOS) which may control basic hardware or software operationsuch as the interaction with peripheral components or devices.

Software 830 may include code to implement aspects of the presentdisclosure, including code to support acknowledgement mechanisms foruplink low latency communications. Software 830 may be stored in anon-transitory computer-readable medium such as system memory or othermemory. In some cases, the software 830 may not be directly executableby the processor but may cause a computer (e.g., when compiled andexecuted) to perform functions described herein.

Transceiver 835 may communicate bi-directionally, via one or moreantennas, wired, or wireless links as described above. For example, thetransceiver 835 may represent a wireless transceiver and may communicatebi-directionally with another wireless transceiver. The transceiver 835may also include a modem to modulate the packets and provide themodulated packets to the antennas for transmission, and to demodulatepackets received from the antennas.

I/O controller 840 may manage input and output signals for device 805.I/O controller 840 may also manage peripherals not integrated intodevice 805. In some cases, I/O controller 840 may represent a physicalconnection or port to an external peripheral. In some cases, I/Ocontroller 840 may utilize an operating system such as iOS®, ANDROID®,MS-DOS®, MS-WINDOWS®, OS/2®, UNIX®, LINUX®, or another known operatingsystem. In other cases, I/O controller 840 may represent or interactwith a modem, a keyboard, a mouse, a touchscreen, or a similar device.In some cases, I/O controller 840 may be implemented as part of aprocessor. In some cases, a user may interact with device 805 via I/Ocontroller 840 or via hardware components controlled by I/O controller840.

FIG. 9 shows a block diagram 900 of a wireless device 905 that supportsacknowledgement mechanisms for uplink low latency communications inaccordance with aspects of the present disclosure. Wireless device 905may be an example of aspects of a URLLC UE 115-a as described herein.Wireless device 905 may include receiver 910, URLLC UE communicationsmanager 915, and transmitter 920. Wireless device 905 may also include aprocessor. Each of these components may be in communication with oneanother (e.g., via one or more buses).

Receiver 910 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related toacknowledgement mechanisms for uplink low latency communications, etc.).Information may be passed on to other components of the device. Thereceiver 910 may be an example of aspects of the transceiver 1135described with reference to FIG. 11. The receiver 910 may utilize asingle antenna or a set of antennas.

URLLC UE communications manager 915 may be an example of aspects of theURLLC UE communications manager 1115 described with reference to FIG.11.

URLLC UE communications manager 915 and/or at least some of its varioussub-components may be implemented in hardware, software executed by aprocessor, firmware, or any combination thereof. If implemented insoftware executed by a processor, the functions of the URLLC UEcommunications manager 915 and/or at least some of its varioussub-components may be executed by a general-purpose processor, a DSP, anASIC, an FPGA or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described in the presentdisclosure. The URLLC UE communications manager 915 and/or at least someof its various sub-components may be physically located at variouspositions, including being distributed such that portions of functionsare implemented at different physical locations by one or more physicaldevices. In some examples, URLLC UE communications manager 915 and/or atleast some of its various sub-components may be a separate and distinctcomponent in accordance with various aspects of the present disclosure.In other examples, URLLC UE communications manager 915 and/or at leastsome of its various sub-components may be combined with one or moreother hardware components, including but not limited to an I/Ocomponent, a transceiver, a network server, another computing device,one or more other components described in the present disclosure, or acombination thereof in accordance with various aspects of the presentdisclosure.

URLLC UE communications manager 915 may receive an assignment of anacknowledgement resource, the acknowledgment resource including a shareddownlink data channel resource available for a downlink datatransmission to one or more other user equipments (UEs), transmit agrant-free uplink transmission, and monitor the acknowledgement resourcefor an acknowledgement of the grant-free uplink transmission.

Alternatively or in addition, URLLC UE communications manager 915 mayreceive an assignment of an acknowledgement resource, the acknowledgmentresource including a shared downlink data channel resource also assignedto one or more other UEs, transmit a grant-free uplink transmission,receive an acknowledgement on the acknowledgement resource, monitor asearch space in a control channel for a grant of uplink transmissionresources for retransmission of data corresponding to the grant-freeuplink transmission, and determine, based on the monitoring, whether theacknowledgement indicates a successful decode of the grant-free uplinktransmission or an unsuccessful decode of the grant-free uplinktransmission.

Transmitter 920 may transmit signals generated by other components ofthe device. In some examples, the transmitter 920 may be collocated witha receiver 910 in a transceiver module. For example, the transmitter 920may be an example of aspects of the transceiver 1135 described withreference to FIG. 11. The transmitter 920 may utilize a single antennaor a set of antennas.

FIG. 10 shows a block diagram 1000 of a wireless device 1005 thatsupports acknowledgement mechanisms for uplink low latencycommunications in accordance with aspects of the present disclosure.Wireless device 1005 may be an example of aspects of a wireless device905 or a URLLC UE 115-a as described with reference to FIG. 9. Wirelessdevice 1005 may include receiver 1010, URLLC UE communications manager1015, and transmitter 1020. Wireless device 1005 may also include aprocessor. Each of these components may be in communication with oneanother (e.g., via one or more buses).

Receiver 1010 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related toacknowledgement mechanisms for uplink low latency communications, etc.).Information may be passed on to other components of the device. Thereceiver 1010 may be an example of aspects of the transceiver 1135described with reference to FIG. 11. The receiver 1010 may utilize asingle antenna or a set of antennas.

URLLC UE communications manager 1015 may be an example of aspects of theURLLC UE communications manager 1115 described with reference to FIG.11.

URLLC UE communications manager 1015 may also include acknowledgementresource assignment manager 1025, URLLC transmission manager 1030,acknowledgement reception manager 1035, uplink grant reception manager1040, and URLLC retransmission manager 1045.

In some examples, acknowledgement resource assignment manager 1025 mayreceive an assignment of an acknowledgement resource, the acknowledgmentresource including a shared downlink data channel resource also assignedto one or more other UEs for downlink data transmission. In some cases,receiving the assignment of the acknowledgement resource includesreceiving a semi-persistent assignment of the acknowledgement resource.In some cases, receiving the assignment of the acknowledgement resourceincludes receiving a dynamic assignment of the acknowledgement resource.In some cases, the shared downlink data channel resource includes aPDSCH.

In some examples, URLLC transmission manager 1030 may transmit agrant-free uplink transmission, retransmit data corresponding to thegrant-free uplink transmission, and transmit data using one or moretransmission resources indicated by the acknowledgement. In some cases,retransmitting data corresponding to the grant-free uplink transmissionincludes retransmitting data corresponding to the grant-free uplinktransmission using one or more transmission resources indicated by theacknowledgement.

In some examples, acknowledgement reception manager 1035 may monitor theacknowledgement resource for an acknowledgement of the grant-free uplinktransmission, receive the acknowledgment, where the acknowledgementincludes a negative acknowledgement indicating that the grant-freeuplink transmission was not successfully received, and receive theacknowledgment, where the acknowledgement includes an affirmativeacknowledgement that the grant-free uplink transmission was successfullyreceived.

In addition or alternatively, in some examples, acknowledgement resourceassignment manager 1025 may receive an assignment of an acknowledgementresource, the acknowledgment resource including a shared downlink datachannel resource also assigned to one or more other UEs (as opposed tobeing assigned on a per-UE basis). In some cases, receiving theassignment of the acknowledgement resource includes receiving asemi-persistent assignment of the acknowledgement resource. In somecases, the shared downlink data channel resource includes a PDSCH.

In the group acknowledgement resource scenario, URLLC transmissionmanager 1030 may transmit a grant-free uplink transmission.

In the group acknowledgement resource scenario, acknowledgementreception manager 1035 may receive an acknowledgement on theacknowledgement resource.

In the group acknowledgement resource scenario, uplink grant receptionmanager 1040 may monitor a search space in a control channel for a grantof uplink transmission resources for retransmission of datacorresponding to the grant-free uplink transmission, evaluate a UEidentifier associated with the potential grant, and receive theacknowledgement and receiving the grant within a single timetransmission interval. In some cases, monitoring the search space in thecontrol channel for the grant of uplink transmission resources includesidentifying within the search space a potential grant of uplinktransmission resources for retransmission of data corresponding to thegrant-free uplink transmission. In some cases, the control channelincludes a PDCCH.

In the group acknowledgement resource scenario, URLLC retransmissionmanager 1045 may determine, based on the monitoring, whether theacknowledgement indicates a successful decode of the grant-free uplinktransmission or an unsuccessful decode of the grant-free uplinktransmission. URLLC retransmission manager 1045 may determine that theacknowledgement indicates an unsuccessful decode of the grant-freeuplink transmission based on determining that the search space includesa grant of uplink transmission resources for retransmission of datacorresponding to the grant-free uplink transmission, and if so, URLLCretransmission manager 1045 may retransmit data corresponding to thegrant-free uplink transmission using uplink transmission resourcesgranted by the grant of uplink transmission resources. Or URLLCretransmission manager 1045 may determine that the acknowledgementindicates a successful decode of the grant-free uplink transmissionbased on determining that the search space lacks a grant of uplinktransmission resources for retransmission of data corresponding to thegrant-free uplink transmission. URLLC retransmission manager 1045 mayalso retransmit data corresponding to the grant-free uplink transmissionvia subsequent grant-free uplink transmissions prior to a terminationevent, where the termination event includes a threshold number ofsubsequent grant-free uplink transmissions, receipt of theacknowledgement, or a combination thereof.

Transmitter 1020 may transmit signals generated by other components ofthe device. In some examples, the transmitter 1020 may be collocatedwith a receiver 1010 in a transceiver module. For example, thetransmitter 1020 may be an example of aspects of the transceiver 1135described with reference to FIG. 11. The transmitter 1020 may utilize asingle antenna or a set of antennas.

FIG. 11 shows a diagram of a system 1100 including a device 1105 thatsupports acknowledgement mechanisms for uplink low latencycommunications in accordance with aspects of the present disclosure.Device 1105 may be an example of or include the components of URLLC UE115-a as described above, e.g., with reference to FIG. 1. Device 1105may include components for bi-directional voice and data communicationsincluding components for transmitting and receiving communications,including URLLC UE communications manager 1115, processor 1120, memory1125, software 1130, transceiver 1135, and I/O controller 1140. Thesecomponents may be in electronic communication via one or more buses(e.g., bus 1110).

Processor 1120 may include an intelligent hardware device, (e.g., ageneral-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, anFPGA, a programmable logic device, a discrete gate or transistor logiccomponent, a discrete hardware component, or any combination thereof).In some cases, processor 1120 may be configured to operate a memoryarray using a memory controller. In other cases, a memory controller maybe integrated into processor 1120. Processor 1120 may be configured toexecute computer-readable instructions stored in a memory to performvarious functions (e.g., functions or tasks supporting acknowledgementmechanisms for uplink low latency communications).

Memory 1125 may include RAM and ROM. The memory 1125 may storecomputer-readable, computer-executable software 1130 includinginstructions that, when executed, cause the processor to perform variousfunctions described herein. In some cases, the memory 1125 may contain,among other things, a BIOS which may control basic hardware or softwareoperation such as the interaction with peripheral components or devices.

Software 1130 may include code to implement aspects of the presentdisclosure, including code to support acknowledgement mechanisms foruplink low latency communications. Software 1130 may be stored in anon-transitory computer-readable medium such as system memory or othermemory. In some cases, the software 1130 may not be directly executableby the processor but may cause a computer (e.g., when compiled andexecuted) to perform functions described herein.

Transceiver 1135 may communicate bi-directionally, via one or moreantennas, wired, or wireless links as described above. For example, thetransceiver 1135 may represent a wireless transceiver and maycommunicate bi-directionally with another wireless transceiver. Thetransceiver 1135 may also include a modem to modulate the packets andprovide the modulated packets to the antennas for transmission, and todemodulate packets received from the antennas.

I/O controller 1140 may manage input and output signals for device 1105.I/O controller 1140 may also manage peripherals not integrated intodevice 1105. In some cases, I/O controller 1140 may represent a physicalconnection or port to an external peripheral. In some cases, I/Ocontroller 1140 may utilize an operating system such as iOS®, ANDROID®,MS-DOS®, MS-WINDOWS®, OS/2®, UNIX®, LINUX®, or another known operatingsystem. In other cases, I/O controller 1140 may represent or interactwith a modem, a keyboard, a mouse, a touchscreen, or a similar device.In some cases, I/O controller 1140 may be implemented as part of aprocessor. In some cases, a user may interact with device 1105 via I/Ocontroller 1140 or via hardware components controlled by I/O controller1140.

FIG. 12 shows a block diagram 1200 of a wireless device 1205 thatsupports acknowledgement mechanisms for uplink low latencycommunications in accordance with aspects of the present disclosure.Wireless device 1205 may be an example of aspects of a non-URLLC UE115-b as described herein. Wireless device 1205 may include receiver1210, non-URLLC UE communications manager 1215, and transmitter 1220.Wireless device 1205 may also include a processor. Each of thesecomponents may be in communication with one another (e.g., via one ormore buses).

Receiver 1210 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related toacknowledgement mechanisms for uplink low latency communications, etc.).Information may be passed on to other components of the device. Thereceiver 1210 may be an example of aspects of the transceiver 1435described with reference to FIG. 14. The receiver 1210 may utilize asingle antenna or a set of antennas.

Non-URLLC UE communications manager 1215 may be an example of aspects ofthe non-URLLC UE communications manager 1415 described with reference toFIG. 14.

Non-URLLC UE communications manager 1215 and/or at least some of itsvarious sub-components may be implemented in hardware, software executedby a processor, firmware, or any combination thereof. If implemented insoftware executed by a processor, the functions of the non-URLLC UEcommunications manager 1215 and/or at least some of its varioussub-components may be executed by a general-purpose processor, a DSP, anASIC, an FPGA or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described in the presentdisclosure. The non-URLLC UE communications manager 1215 and/or at leastsome of its various sub-components may be physically located at variouspositions, including being distributed such that portions of functionsare implemented at different physical locations by one or more physicaldevices. In some examples, non-URLLC UE communications manager 1215and/or at least some of its various sub-components may be a separate anddistinct component in accordance with various aspects of the presentdisclosure. In other examples, non-URLLC UE communications manager 1215and/or at least some of its various sub-components may be combined withone or more other hardware components, including but not limited to anI/O component, a transceiver, a network server, another computingdevice, one or more other components described in the presentdisclosure, or a combination thereof in accordance with various aspectsof the present disclosure.

Non-URLLC UE communications manager 1215 may receive an assignment for ashared downlink data channel resource, the shared downlink data channelresource also assigned to at least one other UE as an acknowledgmentresource, receive a data transmission on the shared downlink datachannel resource, receive an indication that data intended for the UEwas punctured by the received data transmission, and receive asubsequent transmission including punctured data from the datatransmission.

Transmitter 1220 may transmit signals generated by other components ofthe device. In some examples, the transmitter 1220 may be collocatedwith a receiver 1210 in a transceiver module. For example, thetransmitter 1220 may be an example of aspects of the transceiver 1435described with reference to FIG. 14. The transmitter 1220 may utilize asingle antenna or a set of antennas.

FIG. 13 shows a block diagram 1300 of a wireless device 1305 thatsupports acknowledgement mechanisms for uplink low latencycommunications in accordance with aspects of the present disclosure.Wireless device 1305 may be an example of aspects of a wireless device1205 or a non-URLLC UE 115-b as described with reference to FIG. 12.Wireless device 1305 may include receiver 1310, non-URLLC UEcommunications manager 1315, and transmitter 1320. Wireless device 1305may also include a processor. Each of these components may be incommunication with one another (e.g., via one or more buses).

Receiver 1310 may receive information such as packets, user data, orcontrol information associated with various information channels (e.g.,control channels, data channels, and information related toacknowledgement mechanisms for uplink low latency communications, etc.).Information may be passed on to other components of the device. Thereceiver 1310 may be an example of aspects of the transceiver 1435described with reference to FIG. 14. The receiver 1310 may utilize asingle antenna or a set of antennas.

Non-URLLC UE communications manager 1315 may be an example of aspects ofthe non-URLLC UE communications manager 1415 described with reference toFIG. 14.

Non-URLLC UE communications manager 1315 may also include downlink dataassignment manager 1325 and downlink data reception manager 1330.

Downlink data assignment manager 1325 may receive an assignment for ashared downlink data channel resource, the shared downlink data channelresource also assigned to at least one other UE as an acknowledgmentresource. In some cases, the shared downlink data channel resourceincludes a PDSCH.

Downlink data reception manager 1330 may receive a data transmission onthe shared downlink data channel resource, receive an indication thatdata intended for the UE was punctured by the received datatransmission, receive a subsequent transmission including punctured datafrom the data transmission, and receive the indication via a controlchannel, a dedicated indication channel, or a combination thereof. Insome cases, receiving the indication includes receiving informationregarding one or more transmission resources to be used for thesubsequent transmission.

Downlink data processing manager 1335 may discard the data transmissionin the event that downlink data reception manager 1330 receives anindication that data intended for the UE was punctured by the receiveddata transmission.

Transmitter 1320 may transmit signals generated by other components ofthe device. In some examples, the transmitter 1320 may be collocatedwith a receiver 1310 in a transceiver module. For example, thetransmitter 1320 may be an example of aspects of the transceiver 1435described with reference to FIG. 14. The transmitter 1320 may utilize asingle antenna or a set of antennas.

FIG. 14 shows a diagram of a system 1400 including a device 1405 thatsupports acknowledgement mechanisms for uplink low latencycommunications in accordance with aspects of the present disclosure.Device 1405 may be an example of or include the components of non-URLLCUE 115-b as described above, e.g., with reference to FIG. 1. Device 1405may include components for bi-directional voice and data communicationsincluding components for transmitting and receiving communications,including non-URLLC UE communications manager 1415, processor 1420,memory 1425, software 1430, transceiver 1435, and I/O controller 1440.These components may be in electronic communication via one or morebuses (e.g., bus 1410).

Processor 1420 may include an intelligent hardware device, (e.g., ageneral-purpose processor, a DSP, a CPU, a microcontroller, an ASIC, anFPGA, a programmable logic device, a discrete gate or transistor logiccomponent, a discrete hardware component, or any combination thereof).In some cases, processor 1420 may be configured to operate a memoryarray using a memory controller. In other cases, a memory controller maybe integrated into processor 1420. Processor 1420 may be configured toexecute computer-readable instructions stored in a memory to performvarious functions (e.g., functions or tasks supporting acknowledgementmechanisms for uplink low latency communications).

Memory 1425 may include RAM and ROM. The memory 1425 may storecomputer-readable, computer-executable software 1430 includinginstructions that, when executed, cause the processor to perform variousfunctions described herein. In some cases, the memory 1425 may contain,among other things, a BIOS which may control basic hardware or softwareoperation such as the interaction with peripheral components or devices.

Software 1430 may include code to implement aspects of the presentdisclosure, including code to support acknowledgement mechanisms foruplink low latency communications. Software 1430 may be stored in anon-transitory computer-readable medium such as system memory or othermemory. In some cases, the software 1430 may not be directly executableby the processor but may cause a computer (e.g., when compiled andexecuted) to perform functions described herein.

Transceiver 1435 may communicate bi-directionally, via one or moreantennas, wired, or wireless links as described above. For example, thetransceiver 1435 may represent a wireless transceiver and maycommunicate bi-directionally with another wireless transceiver. Thetransceiver 1435 may also include a modem to modulate the packets andprovide the modulated packets to the antennas for transmission, and todemodulate packets received from the antennas.

I/O controller 1440 may manage input and output signals for device 1405.I/O controller 1440 may also manage peripherals not integrated intodevice 1405. In some cases, I/O controller 1440 may represent a physicalconnection or port to an external peripheral. In some cases, I/Ocontroller 1440 may utilize an operating system such as iOS®, ANDROID®,MS-DOS®, MS-WINDOWS®, OS/2®, UNIX®, LINUX®, or another known operatingsystem. In other cases, I/O controller 1440 may represent or interactwith a modem, a keyboard, a mouse, a touchscreen, or a similar device.In some cases, I/O controller 1440 may be implemented as part of aprocessor. In some cases, a user may interact with device 1405 via I/Ocontroller 1440 or via hardware components controlled by I/O controller1440.

FIG. 15 shows a flowchart illustrating a method 1500 for acknowledgementmechanisms for uplink low latency communications in accordance withaspects of the present disclosure. The operations of method 1500 may beimplemented by a base station 105 or its components as described herein.For example, the operations of method 1500 may be performed by a basestation communications manager as described with reference to FIGS. 6through 8. In some examples, a base station 105 may execute a set ofcodes to control the functional elements of the device to perform thefunctions described below. Additionally or alternatively, the basestation 105 may perform aspects of the functions described below usingspecial-purpose hardware.

At block 1505 the base station 105 may assign an acknowledgementresource to a UE, the acknowledgment resource comprising a shareddownlink data channel resource also assigned to one or more other UEsfor a downlink data transmission. The operations of block 1505 may beperformed according to the methods described herein. In certainexamples, aspects of the operations of block 1505 may be performed by anacknowledgement resource assignment manager as described with referenceto FIGS. 6 through 8.

At block 1510 the base station 105 may receive, from the UE, agrant-free uplink transmission. The operations of block 1510 may beperformed according to the methods described herein. In certainexamples, aspects of the operations of block 1510 may be performed by areception manager as described with reference to FIGS. 6 through 8.

At block 1515 the base station 105 may transmit, to the UE via theacknowledgement resource, an acknowledgement of the grant-free uplinktransmission, the acknowledgement puncturing the downlink datatransmission. The operations of block 1515 may be performed according tothe methods described herein. In certain examples, aspects of theoperations of block 1515 may be performed by an acknowledgementtransmission manager as described with reference to FIGS. 6 through 8.

FIG. 16 shows a flowchart illustrating a method 1600 for acknowledgementmechanisms for uplink low latency communications in accordance withaspects of the present disclosure. The operations of method 1600 may beimplemented by a URLLC UE 115-a or its components as described herein.For example, the operations of method 1600 may be performed by a URLLCUE communications manager as described with reference to FIGS. 9 through11. In some examples, a URLLC UE 115-a may execute a set of codes tocontrol the functional elements of the device to perform the functionsdescribed below. Additionally or alternatively, the URLLC UE 115-a mayperform aspects of the functions described below using special-purposehardware.

At block 1605 the URLLC UE 115-a may receive an assignment of anacknowledgement resource, the acknowledgment resource comprising ashared downlink data channel resource also assigned to one or more otherUEs for downlink data transmission. The operations of block 1605 may beperformed according to the methods described herein. In certainexamples, aspects of the operations of block 1605 may be performed by anacknowledgement resource assignment manager as described with referenceto FIGS. 9 through 11.

At block 1610 the URLLC UE 115-a may transmit a grant-free uplinktransmission. The operations of block 1610 may be performed according tothe methods described herein. In certain examples, aspects of theoperations of block 1610 may be performed by a URLLC transmissionmanager as described with reference to FIGS. 9 through 11.

At block 1615 the URLLC UE 115-a may monitor the acknowledgementresource for an acknowledgement of the grant-free uplink transmission.The operations of block 1615 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations ofblock 1615 may be performed by an acknowledgement reception manager asdescribed with reference to FIGS. 9 through 11.

FIG. 17 shows a flowchart illustrating a method 1700 for acknowledgementmechanisms for uplink low latency communications in accordance withaspects of the present disclosure. The operations of method 1700 may beimplemented by a non-URLLC UE 115-b or its components as describedherein. For example, the operations of method 1700 may be performed by anon-URLLC UE communications manager as described with reference to FIGS.12 through 14. In some examples, a non-URLLC UE 115-b may execute a setof codes to control the functional elements of the device to perform thefunctions described below. Additionally or alternatively, the non-URLLCUE 115-b may perform aspects of the functions described below usingspecial-purpose hardware.

At block 1705 the non-URLLC UE 115-b may receive an assignment for ashared downlink data channel resource, the shared downlink data channelresource also assigned to at least one other UE as an acknowledgmentresource. The operations of block 1705 may be performed according to themethods described herein. In certain examples, aspects of the operationsof block 1705 may be performed by a downlink data assignment manager asdescribed with reference to FIGS. 12 through 14.

At block 1710 the non-URLLC UE 115-b may receive a data transmission onthe shared downlink data channel resource. The operations of block 1710may be performed according to the methods described herein. In certainexamples, aspects of the operations of block 1710 may be performed by adownlink data reception manager as described with reference to FIGS. 12through 14.

At block 1715 the non-URLLC UE 115-b may receive an indication that dataintended for the UE was punctured by the received data transmission. Theoperations of block 1715 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations ofblock 1715 may be performed by a downlink data reception manager asdescribed with reference to FIGS. 12 through 14.

At block 1720 the non-URLLC UE 115-b may receive a subsequenttransmission comprising the punctured data. The operations of block 1720may be performed according to the methods described herein. In certainexamples, aspects of the operations of block 1720 may be performed by adownlink data reception manager as described with reference to FIGS. 12through 14.

FIG. 18 shows a flowchart illustrating a method 1800 for acknowledgementmechanisms for uplink low latency communications in accordance withaspects of the present disclosure. The operations of method 1800 may beimplemented by a base station 105 or its components as described herein.For example, the operations of method 1800 may be performed by a basestation communications manager as described with reference to FIGS. 6through 8. In some examples, a base station 105 may execute a set ofcodes to control the functional elements of the device to perform thefunctions described below. Additionally or alternatively, the basestation 105 may perform aspects of the functions described below usingspecial-purpose hardware.

At block 1805 the base station 105 may assign an acknowledgementresource to a UE group comprising a first UE and one or more additionalUEs, the acknowledgment resource comprising a shared downlink datachannel resource. The operations of block 1805 may be performedaccording to the methods described herein. In certain examples, aspectsof the operations of block 1805 may be performed by an acknowledgementresource assignment manager as described with reference to FIGS. 6through 8.

At block 1810 the base station 105 may receive a first grant-free uplinktransmission from the first UE and at least one additional grant-freeuplink transmission from the one or more additional UEs. The operationsof block 1810 may be performed according to the methods describedherein. In certain examples, aspects of the operations of block 1810 maybe performed by a reception manager as described with reference to FIGS.6 through 8.

At block 1815 the base station 105 may transmit, via the acknowledgementresource, an acknowledgement of whether one of the first grant-freeuplink transmission or the at least one additional grant-free uplinktransmission is successfully decoded. The operations of block 1815 maybe performed according to the methods described herein. In certainexamples, aspects of the operations of block 1815 may be performed by anacknowledgement transmission manager as described with reference toFIGS. 6 through 8.

At block 1820 the base station 105 may transmit a grant of uplinktransmission resources for retransmission of data corresponding to anyof the first grant-free uplink transmission or the at least one othergrant-free uplink transmission that is unsuccessfully decoded. Theoperations of block 1820 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations ofblock 1820 may be performed by a uplink grant transmission manager asdescribed with reference to FIGS. 6 through 8.

FIG. 19 shows a flowchart illustrating a method 1900 for acknowledgementmechanisms for uplink low latency communications in accordance withaspects of the present disclosure. The operations of method 1900 may beimplemented by a URLLC UE 115-a or its components as described herein.For example, the operations of method 1900 may be performed by a URLLCUE communications manager as described with reference to FIGS. 9 through11. In some examples, a URLLC UE 115-a may execute a set of codes tocontrol the functional elements of the device to perform the functionsdescribed below. Additionally or alternatively, the URLLC UE 115-a mayperform aspects of the functions described below using special-purposehardware.

At block 1905 the URLLC UE 115-a may receive an assignment of anacknowledgement resource, the acknowledgment resource comprising ashared downlink data channel resource also assigned to one or more otherUEs. The operations of block 1905 may be performed according to themethods described herein. In certain examples, aspects of the operationsof block 1905 may be performed by an acknowledgement resource assignmentmanager as described with reference to FIGS. 9 through 11.

At block 1910 the URLLC UE 115-a may transmit a grant-free uplinktransmission. The operations of block 1910 may be performed according tothe methods described herein. In certain examples, aspects of theoperations of block 1910 may be performed by a URLLC transmissionmanager as described with reference to FIGS. 9 through 11.

At block 1915 the URLLC UE 115-a may receive an acknowledgement on theacknowledgement resource. The operations of block 1915 may be performedaccording to the methods described herein. In certain examples, aspectsof the operations of block 1915 may be performed by an acknowledgementreception manager as described with reference to FIGS. 9 through 11.

At block 1920 the URLLC UE 115-a may monitor a search space in a controlchannel for a grant of uplink transmission resources for retransmissionof data corresponding to the grant-free uplink transmission. Theoperations of block 1920 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations ofblock 1920 may be performed by a uplink grant reception manager asdescribed with reference to FIGS. 9 through 11.

At block 1925 the URLLC UE 115-a may determine, based at least in parton monitoring the search space, whether the acknowledgement indicates asuccessful decode of the grant-free uplink transmission or anunsuccessful decode of the grant-free uplink transmission. Theoperations of block 1925 may be performed according to the methodsdescribed herein. In certain examples, aspects of the operations ofblock 1925 may be performed by a URLLC retransmission manager asdescribed with reference to FIGS. 9 through 11.

It should be noted that the methods described above describe possibleimplementations, and that the operations and the steps may be rearrangedor otherwise modified and that other implementations are possible.Further, aspects from two or more of the methods may be combined.

Techniques described herein may be used for various wirelesscommunications systems such as code division multiple access (CDMA),time division multiple access (TDMA), frequency division multiple access(FDMA), orthogonal frequency division multiple access (OFDMA), singlecarrier frequency division multiple access (SC-FDMA), and other systems.A CDMA system may implement a radio technology such as CDMA2000,Universal Terrestrial Radio Access (UTRA), etc. CDMA2000 covers IS-2000,IS-95, and IS-856 standards. IS-2000 Releases may be commonly referredto as CDMA2000 1×, 1×, etc. IS-856 (TIA-856) is commonly referred to asCDMA2000 1×EV-DO, High Rate Packet Data (HRPD), etc. UTRA includesWideband CDMA (WCDMA) and other variants of CDMA. A TDMA system mayimplement a radio technology such as Global System for MobileCommunications (GSM).

An OFDMA system may implement a radio technology such as Ultra MobileBroadband (UMB), Evolved UTRA (E-UTRA), Institute of Electrical andElectronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE802.20, Flash-OFDM, etc. UTRA and E-UTRA are part of Universal MobileTelecommunications System (UMTS). LTE and LTE-A are releases of UMTSthat use E-UTRA. UTRA, E-UTRA, UMTS, LTE, LTE-A, NR, and GSM aredescribed in documents from the organization named “3rd GenerationPartnership Project” (3GPP). CDMA2000 and UMB are described in documentsfrom an organization named “3rd Generation Partnership Project 2”(3GPP2). The techniques described herein may be used for the systems andradio technologies mentioned above as well as other systems and radiotechnologies. While aspects of an LTE or an NR system may be describedfor purposes of example, and LTE or NR terminology may be used in muchof the description, the techniques described herein are applicablebeyond LTE or NR applications.

A macro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access by UEs115 with service subscriptions with the network provider. A small cellmay be associated with a lower-powered base station 105, as comparedwith a macro cell, and a small cell may operate in the same or different(e.g., licensed, unlicensed, etc.) frequency bands as macro cells. Smallcells may include pico cells, femto cells, and micro cells according tovarious examples. A pico cell, for example, may cover a small geographicarea and may allow unrestricted access by UEs 115 with servicesubscriptions with the network provider. A femto cell may also cover asmall geographic area (e.g., a home) and may provide restricted accessby UEs 115 having an association with the femto cell (e.g., UEs 115 in aclosed subscriber group (CSG), UEs 115 for users in the home, and thelike). An eNB for a macro cell may be referred to as a macro eNB. An eNBfor a small cell may be referred to as a small cell eNB, a pico eNB, afemto eNB, or a home eNB. An eNB may support one or multiple (e.g., two,three, four, and the like) cells, and may also support communicationsusing one or multiple component carriers.

The wireless communications system 100 or systems described herein maysupport synchronous or asynchronous operation. For synchronousoperation, the base stations 105 may have similar frame timing, andtransmissions from different base stations 105 may be approximatelyaligned in time. For asynchronous operation, the base stations 105 mayhave different frame timing, and transmissions from different basestations 105 may not be aligned in time. The techniques described hereinmay be used for either synchronous or asynchronous operations.

Information and signals described herein may be represented using any ofa variety of different technologies and techniques. For example, data,instructions, commands, information, signals, bits, symbols, and chipsthat may be referenced throughout the above description may berepresented by voltages, currents, electromagnetic waves, magneticfields or particles, optical fields or particles, or any combinationthereof.

The various illustrative blocks and modules described in connection withthe disclosure herein may be implemented or performed with ageneral-purpose processor, a digital signal processor (DSP), anapplication-specific integrated circuit (ASIC), a field-programmablegate array (FPGA) or other programmable logic device (PLD), discretegate or transistor logic, discrete hardware components, or anycombination thereof designed to perform the functions described herein.A general-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices (e.g., a combinationof a DSP and a microprocessor, multiple microprocessors, one or moremicroprocessors in conjunction with a DSP core, or any other suchconfiguration).

The functions described herein may be implemented in hardware, softwareexecuted by a processor, firmware, or any combination thereof. Ifimplemented in software executed by a processor, the functions may bestored on or transmitted over as one or more instructions or code on acomputer-readable medium. Other examples and implementations are withinthe scope of the disclosure and appended claims. For example, due to thenature of software, functions described above can be implemented usingsoftware executed by a processor, hardware, firmware, hardwiring, orcombinations of any of these. Features implementing functions may alsobe physically located at various positions, including being distributedsuch that portions of functions are implemented at different physicallocations.

Computer-readable media includes both non-transitory computer storagemedia and communication media including any medium that facilitatestransfer of a computer program from one place to another. Anon-transitory storage medium may be any available medium that can beaccessed by a general purpose or special purpose computer. By way ofexample, and not limitation, non-transitory computer-readable media maycomprise random-access memory (RAM), read-only memory (ROM),electrically erasable programmable read only memory (EEPROM), flashmemory, compact disk (CD) ROM or other optical disk storage, magneticdisk storage or other magnetic storage devices, or any othernon-transitory medium that can be used to carry or store desired programcode means in the form of instructions or data structures and that canbe accessed by a general-purpose or special-purpose computer, or ageneral-purpose or special-purpose processor. Also, any connection isproperly termed a computer-readable medium. For example, if the softwareis transmitted from a website, server, or other remote source using acoaxial cable, fiber optic cable, twisted pair, digital subscriber line(DSL), or wireless technologies such as infrared, radio, and microwave,then the coaxial cable, fiber optic cable, twisted pair, DSL, orwireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,include CD, laser disc, optical disc, digital versatile disc (DVD),floppy disk and Blu-ray disc where disks usually reproduce datamagnetically, while discs reproduce data optically with lasers.Combinations of the above are also included within the scope ofcomputer-readable media.

As used herein, including in the claims, “or” as used in a list of items(e.g., a list of items prefaced by a phrase such as “at least one of” or“one or more of”) indicates an inclusive list such that, for example, alist of at least one of A, B, or C means A or B or C or AB or AC or BCor ABC (i.e., A and B and C). Also, as used herein, the phrase “basedon” shall not be construed as a reference to a closed set of conditions.For example, an exemplary step that is described as “based on conditionA” may be based on both a condition A and a condition B withoutdeparting from the scope of the present disclosure. In other words, asused herein, the phrase “based on” shall be construed in the same manneras the phrase “based at least in part on.”

In the appended figures, similar components or features may have thesame reference label. Further, various components of the same type maybe distinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label, or othersubsequent reference label.

The description set forth herein, in connection with the appendeddrawings, describes example configurations and does not represent allthe examples that may be implemented or that are within the scope of theclaims. The term “exemplary” used herein means “serving as an example,instance, or illustration,” and not “preferred” or “advantageous overother examples.” The detailed description includes specific details forthe purpose of providing an understanding of the described techniques.These techniques, however, may be practiced without these specificdetails. In some instances, well-known structures and devices are shownin block diagram form in order to avoid obscuring the concepts of thedescribed examples.

The description herein is provided to enable a person skilled in the artto make or use the disclosure. Various modifications to the disclosurewill be readily apparent to those skilled in the art, and the genericprinciples defined herein may be applied to other variations withoutdeparting from the scope of the disclosure. Thus, the disclosure is notlimited to the examples and designs described herein, but is to beaccorded the broadest scope consistent with the principles and novelfeatures disclosed herein.

What is claimed is:
 1. A method for wireless communication, comprising:assigning an acknowledgement resource to a user equipment (UE) of afirst service type, the acknowledgement resource comprising a shareddownlink data channel resource also assigned to one or more other UEs ofa second service type different from the first service type for adownlink data transmission, wherein the first service type is associatedwith a first latency requirement for data communication that has alatency requirement different from a second latency requirement for datacommunication with which the second service type is associated;receiving, from the UE of the first service type, a grant-free uplinktransmission; and transmitting, to the UE of the first service type viathe acknowledgement resource, an acknowledgement of the grant-freeuplink transmission, the acknowledgement puncturing the downlink datatransmission to the one or more other UEs of the second service type. 2.The method of claim 1, further comprising: transmitting to the one ormore other UEs of the second service type an indication of thepuncturing.
 3. The method of claim 2, further comprising: transmittingthe acknowledgement and transmitting the indication in a sametransmission time interval.
 4. The method of claim 2, furthercomprising: transmitting the acknowledgement in a first transmissiontime interval and transmitting the indication in a second transmissiontime interval, the second transmission time interval subsequent to thefirst transmission time interval.
 5. The method of claim 2, furthercomprising: transmitting the indication via a control channel, adedicated indication channel, or a combination thereof.
 6. The method ofclaim 2, wherein transmitting the indication of the puncturingcomprises: transmitting information regarding a subsequent transmission,the subsequent transmission comprising data punctured by theacknowledgement.
 7. The method of claim 1, further comprising: receivingdata from the UE of the first service type via one or more transmissionresources indicated by the acknowledgement.
 8. The method of claim 1,wherein assigning, to the UE of the first service type, theacknowledgement resource comprises: semi-persistently assigning aUE-specific acknowledgement resource to the UE of the first servicetype.
 9. The method of claim 1, wherein assigning, to the UE of thefirst service type, the acknowledgement resource comprises: dynamicallyassigning the acknowledgement resource to the UE of the first servicetype.
 10. The method of claim 1, wherein: the grant-free uplinktransmission is for ultra-reliable communications, low latencycommunications, or a combination thereof.
 11. The method of claim 1,wherein: the downlink data transmission is for enhanced mobile broadbandcommunications.
 12. The method of claim 1, wherein: the shared downlinkdata channel resource comprises a physical downlink shared channel(PDSCH).
 13. The method of claim 1, further comprising: receiving atleast one additional grant-free uplink transmission from one or moreadditional UEs apart from the UE of the first service type; determiningthat at least some data received with the at least one additionalgrant-free uplink transmission from the one or more additional UEs isunsuccessfully decoded; and transmitting, based at least in part on atleast some data being unsuccessfully decoded, a grant of uplinktransmission resources in response to the at least one additionalgrant-free uplink transmission from the one or more additional UEs. 14.The method of claim 13, wherein transmitting the grant of uplinktransmission resources comprises: transmitting the grant of uplinktransmission resources within a search space in a control channel alongwith an indication of whether the grant of uplink transmission resourcesis for the UE or for the one or more additional UEs apart from the UE ofthe first service type.
 15. A method for wireless communication,comprising: receiving, by a user equipment (UE) of a first service type,an assignment of an acknowledgement resource, the acknowledgementresource comprising a shared downlink data channel resource availablefor a downlink data transmission to one or more other UEs of a secondservice type different from the first service type, wherein the firstservice type is associated with a first latency requirement for datacommunication that has a latency requirement different from a secondlatency requirement for data communication with which the second servicetype is associated; transmitting a grant-free uplink transmission;monitoring the acknowledgement resource for an acknowledgement of thegrant-free uplink transmission; and receiving, from a base station viathe acknowledgement resource, the acknowledgement of the grant-freeuplink transmission, the acknowledgement puncturing the downlink datatransmission to the one or more other UEs of the second service type.16. The method of claim 15, wherein the acknowledgement comprises anegative acknowledgement indicating that the grant-free uplinktransmission was not successfully received, and the method furthercomprising: retransmitting data corresponding to the grant-free uplinktransmission.
 17. The method of claim 16, wherein retransmitting datacorresponding to the grant-free uplink transmission comprises:retransmitting data corresponding to the grant-free uplink transmissionusing one or more transmission resources indicated by theacknowledgement.
 18. The method of claim 15, wherein the acknowledgementcomprises an affirmative acknowledgement that the grant-free uplinktransmission was successfully received and the method furthercomprising: transmitting data using one or more transmission resourcesindicated by the acknowledgement.
 19. The method of claim 15, whereinreceiving the assignment of the acknowledgement resource comprises:receiving a semi-persistent assignment of a UE-specific acknowledgementresource.
 20. The method of claim 15, wherein receiving the assignmentof the acknowledgement resource comprises: receiving a dynamicassignment of the acknowledgement resource.
 21. The method of claim 15,wherein: the shared downlink data channel resource comprises a physicaldownlink shared channel (PDSCH).
 22. The method of claim 15, furthercomprising: monitoring, based at least in part on receiving theacknowledgement of the grant-free uplink transmission, a search space ina control channel for a grant of uplink transmission resources forretransmission of data corresponding to the grant-free uplinktransmission; and determining, based at least in part on monitoring thesearch space, whether the acknowledgement indicates a successful decodeof the grant-free uplink transmission or an unsuccessful decode of thegrant-free uplink transmission.
 23. The method of claim 22, furthercomprising: determining that the acknowledgement indicates theunsuccessful decode of the grant-free uplink transmission based at leastin part on determining that the search space includes the grant ofuplink transmission resources for retransmission of data correspondingto the grant-free uplink transmission.
 24. The method of claim 23,further comprising: retransmitting data corresponding to the grant-freeuplink transmission using uplink transmission resources granted by thegrant of uplink transmission resources.
 25. A method for wirelesscommunication at a user equipment (UE) of a second service typedifferent from a first service type, comprising: receiving, by the UE ofthe second service type, an assignment for a shared downlink datachannel resource, the shared downlink data channel resource alsoassigned to at least one other UE of the first service type as anacknowledgement resource, wherein the first service type is associatedwith a first latency requirement for data communication that has alatency requirement different from a second latency requirement for datacommunication with which the second service type is associated;receiving a data transmission on the shared downlink data channelresource; receiving an indication that data intended for the UE of thesecond service type was punctured by the received data transmission; andreceiving a subsequent transmission comprising the punctured data. 26.The method of claim 25, further comprising: discarding the datatransmission based at least in part on the indication.
 27. The method ofclaim 25, further comprising: receiving the indication via a controlchannel, a dedicated indication channel, or a combination thereof. 28.The method of claim 25, wherein receiving the indication comprises:receiving information regarding one or more transmission resources to beused for the subsequent transmission.
 29. The method of claim 25,wherein: the shared downlink data channel resource comprises a physicaldownlink shared channel (PDSCH).
 30. An apparatus for wirelesscommunication, comprising: a processor; memory coupled to the processor;and instructions stored in the memory and operable, when executed by theprocessor, to cause the apparatus to: receive, by a user equipment (UE)of a first service type, an assignment of an acknowledgement resource,the acknowledgement resource comprising a shared downlink data channelresource available for a downlink data transmission to one or more otherUEs of a second service type different from the first service type,wherein the first service type is associated with a first latencyrequirement for data communication that has a latency requirementdifferent from a second latency requirement for data communication withwhich the second service type is associated; transmit a grant-freeuplink transmission; monitor the acknowledgement resource for anacknowledgement of the grant-free uplink transmission; and receive, froma base station via the acknowledgement resource, the acknowledgement ofthe grant-free uplink transmission, the acknowledgement puncturing thedownlink data transmission to the one or more other UEs of the secondservice type.